| Message ID | 20200319212801.2726275-1-polacek@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: template keyword in a typename-specifier [PR94057] | expand |
On 3/19/20 5:28 PM, Marek Polacek wrote: > Consider > > template <typename T> class A { > template <typename U> class B { > void fn(typename A<T>::B<U>); > }; > }; > > which is rejected with > error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type > whereas clang/icc/msvc accept it. > > "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments > don't mention it anywhere, because the typename-specifier wasn't in C++11; > it was only added to the language in N1376. Instead, we handle it as > an elaborated-type-specifier (not a problem thus far). So we get to > cp_parser_nested_name_specifier_opt which has a loop that breaks if we > don't see a < or ::, but that means we can -- tentatively -- parse even > B<U> which is not a nested-name-specifier (it doesn't end with a ::). > > Even though we're parsing B<U> tentatively, we issue an error in > cp_parser_class_name -> make_typename_type, but here we should not. In > fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the > cp_parser_class_name hunk. > > I think this should compile because [temp.names]/4 says: "In a qualified-id > used as the name in a typename-specifier, elaborated-type-specifier, > using-declaration, or class-or-decltype, an optional keyword template > appearing at the top level is ignored.", added in DR 1710. Also see > DR 1812. Looks good, but please add tests for the other contexts mentioned in that passage. > This issue on its own is not a significant problem or a regression. > However, in C++20, the typename here becomes optional, and so this test > is rejected in C++20, but accepted in C++17: > > template <typename T> class A { > template <typename U> class B { > void fn(A<T>::B<U>); > }; > }; > > Here we morph A<T>::B<U> into a typename-specifier, but that happens > in cp_parser_simple_type_specifier and we never handle it as above. > To fake the template keyword I'm afraid we need to use cp_parser_template_id > with template_keyword_p=true as in the patch below. The tricky thing > is to avoid breaking concepts. > > Does this approach make sense? Should these tests be accepted because > of DR 1710 or am I off base here? > > Apologies for the verbosity, but I felt it necessary. Verbosity isn't a problem. :) > Bootstrapped/regtested on x86_64-linux, built Boost/cmcstl2, ok for trunk? > > PR c++/94057 - template keyword in a typename-specifier. > * parser.c (cp_parser_simple_type_specifier): Assume that a < > following a qualified-id in a typename-specifier begins > a template argument list. > (cp_parser_class_name): Complain only if not parsing tentatively. > > * g++.dg/template/dependent-name5.C: Update dg-error. > * g++.dg/template/dependent-name7.C: New test. > * g++.dg/template/dependent-name8.C: New test. > * g++.dg/template/dependent-name9.C: New test. > --- > gcc/cp/parser.c | 32 +++++++++++++++++-- > .../g++.dg/template/dependent-name5.C | 2 -- > .../g++.dg/template/dependent-name7.C | 9 ++++++ > .../g++.dg/template/dependent-name8.C | 9 ++++++ > .../g++.dg/template/dependent-name9.C | 9 ++++++ > 5 files changed, 57 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index cbd5510a8fb..f4175955992 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -18113,6 +18113,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, > } > } > } > + /* DR 1812: A < following a qualified-id in a typename-specifier > + could safely be assumed to begin a template argument list, so > + the template keyword should be optional. */ > + else if (parser->scope > + && qualified_p > + && typename_p > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) > + { > + cp_parser_parse_tentatively (parser); > + > + type = cp_parser_template_id (parser, > + /*template_keyword_p=*/true, > + /*check_dependency_p=*/true, > + none_type, > + /*is_declaration=*/false); > + /* This is handled below, so back off. */ > + if (type && concept_check_p (type)) > + cp_parser_simulate_error (parser); > + > + if (!cp_parser_parse_definitely (parser)) > + type = NULL_TREE; > + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) > + type = make_typename_type (parser->scope, type, typename_type, > + /*complain=*/tf_error); > + else if (TREE_CODE (type) != TYPE_DECL) > + type = NULL_TREE; > + } > > /* Otherwise, look for a type-name. */ > if (!type) > @@ -23636,8 +23663,9 @@ cp_parser_class_name (cp_parser *parser, > && decl != error_mark_node > && !is_overloaded_fn (decl)) > { > - decl = make_typename_type (scope, decl, typename_type, > - /*complain=*/tf_error); > + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) > + ? tf_none : tf_error); > + decl = make_typename_type (scope, decl, typename_type, complain); > if (decl != error_mark_node) > decl = TYPE_NAME (decl); > } > diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C > index fc78983324b..15c1acb0347 100644 > --- a/gcc/testsuite/g++.dg/template/dependent-name5.C > +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C > @@ -22,9 +22,7 @@ struct A > > typedef N<int> type6; > typedef A::N<int> type7; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T>::N<int> type8; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } > typedef typename A<T*>::template N<int> type10; > > diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C > new file mode 100644 > index 00000000000..3dfa42d2df0 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(A<T>::B<U>&); > + void fn(A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C > new file mode 100644 > index 00000000000..ad9e44f9b85 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::B<U>&); > + void fn(typename A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C > new file mode 100644 > index 00000000000..6dfdbc176c1 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::template B<U>&); > + void fn(typename A<T>::template B<U>); > + }; > +}; > > base-commit: f22712bd8a2ed57d3cc7e6fa92730bd5852e27b3 >
On Thu, Mar 19, 2020 at 05:40:01PM -0400, Jason Merrill wrote: > On 3/19/20 5:28 PM, Marek Polacek wrote: > > Consider > > > > template <typename T> class A { > > template <typename U> class B { > > void fn(typename A<T>::B<U>); > > }; > > }; > > > > which is rejected with > > error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type > > whereas clang/icc/msvc accept it. > > > > "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments > > don't mention it anywhere, because the typename-specifier wasn't in C++11; > > it was only added to the language in N1376. Instead, we handle it as > > an elaborated-type-specifier (not a problem thus far). So we get to > > cp_parser_nested_name_specifier_opt which has a loop that breaks if we > > don't see a < or ::, but that means we can -- tentatively -- parse even > > B<U> which is not a nested-name-specifier (it doesn't end with a ::). > > > > Even though we're parsing B<U> tentatively, we issue an error in > > cp_parser_class_name -> make_typename_type, but here we should not. In > > fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the > > cp_parser_class_name hunk. > > > > I think this should compile because [temp.names]/4 says: "In a qualified-id > > used as the name in a typename-specifier, elaborated-type-specifier, > > using-declaration, or class-or-decltype, an optional keyword template > > appearing at the top level is ignored.", added in DR 1710. Also see > > DR 1812. > > Looks good, but please add tests for the other contexts mentioned in that > passage. Wonderful. I've added a bunch of tests, and some from the related DRs too. But I had a problem with the class-or-decltype case: if we have template<typename T> struct D : T::template B<int>::template C<int> {}; then we still require all the 'template' keywords here (as does clang). So I'm kind of confused, but I don't think it's a big deal right now. Bootstrapped/regtested on x86_64-linux, ok for trunk? -- >8 -- Consider template <typename T> class A { template <typename U> class B { void fn(typename A<T>::B<U>); }; }; which is rejected with error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type whereas clang/icc/msvc accept it. "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments don't mention it anywhere, because the typename-specifier wasn't in C++11; it was only added to the language in N1376. Instead, we handle it as an elaborated-type-specifier (not a problem thus far). So we get to cp_parser_nested_name_specifier_opt which has a loop that breaks if we don't see a < or ::, but that means we can -- tentatively -- parse even B<U> which is not a nested-name-specifier (it doesn't end with a ::). Even though we're parsing B<U> tentatively, we issue an error in cp_parser_class_name -> make_typename_type, but here we should not. In fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the cp_parser_class_name hunk. I think this should compile because [temp.names]/4 says: "In a qualified-id used as the name in a typename-specifier, elaborated-type-specifier, using-declaration, or class-or-decltype, an optional keyword template appearing at the top level is ignored.", added in DR 1710. Also see DR 1812. This issue on its own is not a significant problem or a regression. However, in C++20, the typename here becomes optional, and so this test is rejected in C++20, but accepted in C++17: template <typename T> class A { template <typename U> class B { void fn(A<T>::B<U>); }; }; Here we morph A<T>::B<U> into a typename-specifier, but that happens in cp_parser_simple_type_specifier and we never handle it as above. To fake the template keyword I'm afraid we need to use cp_parser_template_id with template_keyword_p=true as in the patch below. The tricky thing is to avoid breaking concepts. DR 1710 PR c++/94057 - template keyword in a typename-specifier. * parser.c (cp_parser_simple_type_specifier): Assume that a < following a qualified-id in a typename-specifier begins a template argument list. (cp_parser_class_name): Complain only if not parsing tentatively. * g++.dg/template/dependent-name5.C: Update dg-error. * g++.dg/template/dependent-name7.C: New test. * g++.dg/template/dependent-name8.C: New test. * g++.dg/template/dependent-name9.C: New test. * g++.dg/template/dependent-name10.C: New test. * g++.dg/template/dependent-name11.C: New test. * g++.dg/template/dr1794.C: New test. * g++.dg/template/dr314.C: New test. * g++.dg/template/dr1710.C: New test. --- gcc/cp/parser.c | 32 +++++++++++++++++-- .../g++.dg/template/dependent-name10.C | 18 +++++++++++ .../g++.dg/template/dependent-name11.C | 15 +++++++++ .../g++.dg/template/dependent-name5.C | 2 -- .../g++.dg/template/dependent-name7.C | 9 ++++++ .../g++.dg/template/dependent-name8.C | 9 ++++++ .../g++.dg/template/dependent-name9.C | 9 ++++++ gcc/testsuite/g++.dg/template/dr1710.C | 4 +++ gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++++++ gcc/testsuite/g++.dg/template/dr314.C | 11 +++++++ 10 files changed, 119 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C create mode 100644 gcc/testsuite/g++.dg/template/dr314.C diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index cbd5510a8fb..f4175955992 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -18113,6 +18113,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, } } } + /* DR 1812: A < following a qualified-id in a typename-specifier + could safely be assumed to begin a template argument list, so + the template keyword should be optional. */ + else if (parser->scope + && qualified_p + && typename_p + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) + { + cp_parser_parse_tentatively (parser); + + type = cp_parser_template_id (parser, + /*template_keyword_p=*/true, + /*check_dependency_p=*/true, + none_type, + /*is_declaration=*/false); + /* This is handled below, so back off. */ + if (type && concept_check_p (type)) + cp_parser_simulate_error (parser); + + if (!cp_parser_parse_definitely (parser)) + type = NULL_TREE; + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) + type = make_typename_type (parser->scope, type, typename_type, + /*complain=*/tf_error); + else if (TREE_CODE (type) != TYPE_DECL) + type = NULL_TREE; + } /* Otherwise, look for a type-name. */ if (!type) @@ -23636,8 +23663,9 @@ cp_parser_class_name (cp_parser *parser, && decl != error_mark_node && !is_overloaded_fn (decl)) { - decl = make_typename_type (scope, decl, typename_type, - /*complain=*/tf_error); + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) + ? tf_none : tf_error); + decl = make_typename_type (scope, decl, typename_type, complain); if (decl != error_mark_node) decl = TYPE_NAME (decl); } diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C new file mode 100644 index 00000000000..18e024f7e6d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C @@ -0,0 +1,18 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> struct B { + typedef int TT; + typedef int TT2; + typedef int TT3; + typedef int TT4; + }; +}; + +struct X : A<int>::B<int> { + using A<int>::template B<int>::TT; + using typename A<int>::template B<int>::TT2; + using A<int>::B<int>::TT3; + using typename A<int>::B<int>::TT4; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C new file mode 100644 index 00000000000..687a9bd5df5 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C @@ -0,0 +1,15 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> + struct W { }; +}; + +void +g () +{ + // class-key nested-name-specifier template[opt] simple-template-id + struct A<int>::W<int> w; + struct A<int>::template W<int> w2; +} diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C index fc78983324b..15c1acb0347 100644 --- a/gcc/testsuite/g++.dg/template/dependent-name5.C +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C @@ -22,9 +22,7 @@ struct A typedef N<int> type6; typedef A::N<int> type7; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T>::N<int> type8; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } typedef typename A<T*>::template N<int> type10; diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C new file mode 100644 index 00000000000..3dfa42d2df0 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(A<T>::B<U>&); + void fn(A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C new file mode 100644 index 00000000000..ad9e44f9b85 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::B<U>&); + void fn(typename A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C new file mode 100644 index 00000000000..6dfdbc176c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::template B<U>&); + void fn(typename A<T>::template B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C new file mode 100644 index 00000000000..fbbccde9bbf --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710.C @@ -0,0 +1,4 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct D : T::template B<int>::template C<int> {}; diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C new file mode 100644 index 00000000000..f629d7d0b98 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1794.C @@ -0,0 +1,14 @@ +// DR 1794 - template keyword and alias templates. +// { dg-do compile { target c++11 } } + +template<template<typename> class Template> +struct Internal { + template<typename Arg> + using Bind = Template<Arg>; +}; + +template<template<typename> class Template, typename Arg> +using Instantiate = Template<Arg>; + +template<template<typename> class Template, typename Argument> +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C new file mode 100644 index 00000000000..e3c9c9e5a0e --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr314.C @@ -0,0 +1,11 @@ +// DR 314 - template in base class specifier. + +template <typename T> +struct A { + template <typename U> + struct B {}; +}; + +template <typename T> +struct C : public A<T>::template B<T> { +}; base-commit: 3d42842c07f4143042f3dcc39a050b262bcf1b55
On 3/20/20 1:06 PM, Marek Polacek wrote: > On Thu, Mar 19, 2020 at 05:40:01PM -0400, Jason Merrill wrote: >> On 3/19/20 5:28 PM, Marek Polacek wrote: >>> Consider >>> >>> template <typename T> class A { >>> template <typename U> class B { >>> void fn(typename A<T>::B<U>); >>> }; >>> }; >>> >>> which is rejected with >>> error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type >>> whereas clang/icc/msvc accept it. >>> >>> "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments >>> don't mention it anywhere, because the typename-specifier wasn't in C++11; >>> it was only added to the language in N1376. Instead, we handle it as >>> an elaborated-type-specifier (not a problem thus far). So we get to >>> cp_parser_nested_name_specifier_opt which has a loop that breaks if we >>> don't see a < or ::, but that means we can -- tentatively -- parse even >>> B<U> which is not a nested-name-specifier (it doesn't end with a ::). >>> >>> Even though we're parsing B<U> tentatively, we issue an error in >>> cp_parser_class_name -> make_typename_type, but here we should not. In >>> fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the >>> cp_parser_class_name hunk. >>> >>> I think this should compile because [temp.names]/4 says: "In a qualified-id >>> used as the name in a typename-specifier, elaborated-type-specifier, >>> using-declaration, or class-or-decltype, an optional keyword template >>> appearing at the top level is ignored.", added in DR 1710. Also see >>> DR 1812. >> >> Looks good, but please add tests for the other contexts mentioned in that >> passage. > > Wonderful. I've added a bunch of tests, and some from the related DRs too. > But I had a problem with the class-or-decltype case: if we have > > template<typename T> struct D : T::template B<int>::template C<int> {}; > > then we still require all the 'template' keywords here (as does clang). So I'm > kind of confused, but I don't think it's a big deal right now. This seems related enough that I'd like to fix it at the same time; why doesn't your patch fix it? Is it because typename_p is false? > Bootstrapped/regtested on x86_64-linux, ok for trunk? > > -- >8 -- > Consider > > template <typename T> class A { > template <typename U> class B { > void fn(typename A<T>::B<U>); > }; > }; > > which is rejected with > error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type > whereas clang/icc/msvc accept it. > > "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments > don't mention it anywhere, because the typename-specifier wasn't in C++11; > it was only added to the language in N1376. Instead, we handle it as > an elaborated-type-specifier (not a problem thus far). So we get to > cp_parser_nested_name_specifier_opt which has a loop that breaks if we > don't see a < or ::, but that means we can -- tentatively -- parse even > B<U> which is not a nested-name-specifier (it doesn't end with a ::). > > Even though we're parsing B<U> tentatively, we issue an error in > cp_parser_class_name -> make_typename_type, but here we should not. In > fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the > cp_parser_class_name hunk. > > I think this should compile because [temp.names]/4 says: "In a qualified-id > used as the name in a typename-specifier, elaborated-type-specifier, > using-declaration, or class-or-decltype, an optional keyword template > appearing at the top level is ignored.", added in DR 1710. Also see > DR 1812. > > This issue on its own is not a significant problem or a regression. > However, in C++20, the typename here becomes optional, and so this test > is rejected in C++20, but accepted in C++17: > > template <typename T> class A { > template <typename U> class B { > void fn(A<T>::B<U>); > }; > }; > > Here we morph A<T>::B<U> into a typename-specifier, but that happens > in cp_parser_simple_type_specifier and we never handle it as above. > To fake the template keyword I'm afraid we need to use cp_parser_template_id > with template_keyword_p=true as in the patch below. The tricky thing > is to avoid breaking concepts. > > DR 1710 > PR c++/94057 - template keyword in a typename-specifier. > * parser.c (cp_parser_simple_type_specifier): Assume that a < > following a qualified-id in a typename-specifier begins > a template argument list. > (cp_parser_class_name): Complain only if not parsing tentatively. > > * g++.dg/template/dependent-name5.C: Update dg-error. > * g++.dg/template/dependent-name7.C: New test. > * g++.dg/template/dependent-name8.C: New test. > * g++.dg/template/dependent-name9.C: New test. > * g++.dg/template/dependent-name10.C: New test. > * g++.dg/template/dependent-name11.C: New test. > * g++.dg/template/dr1794.C: New test. > * g++.dg/template/dr314.C: New test. > * g++.dg/template/dr1710.C: New test. Please also add the parallel tests omitting the template keyword. > --- > gcc/cp/parser.c | 32 +++++++++++++++++-- > .../g++.dg/template/dependent-name10.C | 18 +++++++++++ > .../g++.dg/template/dependent-name11.C | 15 +++++++++ > .../g++.dg/template/dependent-name5.C | 2 -- > .../g++.dg/template/dependent-name7.C | 9 ++++++ > .../g++.dg/template/dependent-name8.C | 9 ++++++ > .../g++.dg/template/dependent-name9.C | 9 ++++++ > gcc/testsuite/g++.dg/template/dr1710.C | 4 +++ > gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++++++ > gcc/testsuite/g++.dg/template/dr314.C | 11 +++++++ > 10 files changed, 119 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C > create mode 100644 gcc/testsuite/g++.dg/template/dr314.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index cbd5510a8fb..f4175955992 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -18113,6 +18113,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, > } > } > } > + /* DR 1812: A < following a qualified-id in a typename-specifier > + could safely be assumed to begin a template argument list, so > + the template keyword should be optional. */ > + else if (parser->scope > + && qualified_p > + && typename_p > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) > + { > + cp_parser_parse_tentatively (parser); > + > + type = cp_parser_template_id (parser, > + /*template_keyword_p=*/true, > + /*check_dependency_p=*/true, > + none_type, > + /*is_declaration=*/false); > + /* This is handled below, so back off. */ > + if (type && concept_check_p (type)) > + cp_parser_simulate_error (parser); > + > + if (!cp_parser_parse_definitely (parser)) > + type = NULL_TREE; > + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) > + type = make_typename_type (parser->scope, type, typename_type, > + /*complain=*/tf_error); > + else if (TREE_CODE (type) != TYPE_DECL) > + type = NULL_TREE; > + } > > /* Otherwise, look for a type-name. */ > if (!type) > @@ -23636,8 +23663,9 @@ cp_parser_class_name (cp_parser *parser, > && decl != error_mark_node > && !is_overloaded_fn (decl)) > { > - decl = make_typename_type (scope, decl, typename_type, > - /*complain=*/tf_error); > + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) > + ? tf_none : tf_error); > + decl = make_typename_type (scope, decl, typename_type, complain); > if (decl != error_mark_node) > decl = TYPE_NAME (decl); > } > diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C > new file mode 100644 > index 00000000000..18e024f7e6d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C > @@ -0,0 +1,18 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> struct B { > + typedef int TT; > + typedef int TT2; > + typedef int TT3; > + typedef int TT4; > + }; > +}; > + > +struct X : A<int>::B<int> { > + using A<int>::template B<int>::TT; > + using typename A<int>::template B<int>::TT2; > + using A<int>::B<int>::TT3; > + using typename A<int>::B<int>::TT4; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C > new file mode 100644 > index 00000000000..687a9bd5df5 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C > @@ -0,0 +1,15 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> > + struct W { }; > +}; > + > +void > +g () > +{ > + // class-key nested-name-specifier template[opt] simple-template-id > + struct A<int>::W<int> w; > + struct A<int>::template W<int> w2; > +} > diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C > index fc78983324b..15c1acb0347 100644 > --- a/gcc/testsuite/g++.dg/template/dependent-name5.C > +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C > @@ -22,9 +22,7 @@ struct A > > typedef N<int> type6; > typedef A::N<int> type7; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T>::N<int> type8; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } > typedef typename A<T*>::template N<int> type10; > > diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C > new file mode 100644 > index 00000000000..3dfa42d2df0 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(A<T>::B<U>&); > + void fn(A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C > new file mode 100644 > index 00000000000..ad9e44f9b85 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::B<U>&); > + void fn(typename A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C > new file mode 100644 > index 00000000000..6dfdbc176c1 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::template B<U>&); > + void fn(typename A<T>::template B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C > new file mode 100644 > index 00000000000..fbbccde9bbf > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710.C > @@ -0,0 +1,4 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct D : T::template B<int>::template C<int> {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C > new file mode 100644 > index 00000000000..f629d7d0b98 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1794.C > @@ -0,0 +1,14 @@ > +// DR 1794 - template keyword and alias templates. > +// { dg-do compile { target c++11 } } > + > +template<template<typename> class Template> > +struct Internal { > + template<typename Arg> > + using Bind = Template<Arg>; > +}; > + > +template<template<typename> class Template, typename Arg> > +using Instantiate = Template<Arg>; > + > +template<template<typename> class Template, typename Argument> > +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; > diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C > new file mode 100644 > index 00000000000..e3c9c9e5a0e > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr314.C > @@ -0,0 +1,11 @@ > +// DR 314 - template in base class specifier. > + > +template <typename T> > +struct A { > + template <typename U> > + struct B {}; > +}; > + > +template <typename T> > +struct C : public A<T>::template B<T> { > +}; > > base-commit: 3d42842c07f4143042f3dcc39a050b262bcf1b55 >
On Fri, Mar 20, 2020 at 02:12:49PM -0400, Jason Merrill wrote: > On 3/20/20 1:06 PM, Marek Polacek wrote: > > Wonderful. I've added a bunch of tests, and some from the related DRs too. > > But I had a problem with the class-or-decltype case: if we have > > > > template<typename T> struct D : T::template B<int>::template C<int> {}; > > > > then we still require all the 'template' keywords here (as does clang). So I'm > > kind of confused, but I don't think it's a big deal right now. > > This seems related enough that I'd like to fix it at the same time; why > doesn't your patch fix it? Is it because typename_p is false? Ah, I was mistaken. Of course we need the template keyword here: it's a member of an unknown specialization! So I think there's no problem, and I've... > > * g++.dg/template/dependent-name5.C: Update dg-error. > > * g++.dg/template/dependent-name7.C: New test. > > * g++.dg/template/dependent-name8.C: New test. > > * g++.dg/template/dependent-name9.C: New test. > > * g++.dg/template/dependent-name10.C: New test. > > * g++.dg/template/dependent-name11.C: New test. > > * g++.dg/template/dr1794.C: New test. > > * g++.dg/template/dr314.C: New test. > > * g++.dg/template/dr1710.C: New test. > > Please also add the parallel tests omitting the template keyword. ...added some tests to that effect (added dr1710-2.C, expanded dr314.C). Sorry about the confusion. Is is OK now? Thanks, -- >8 -- Consider template <typename T> class A { template <typename U> class B { void fn(typename A<T>::B<U>); }; }; which is rejected with error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type whereas clang/icc/msvc accept it. "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments don't mention it anywhere, because the typename-specifier wasn't in C++11; it was only added to the language in N1376. Instead, we handle it as an elaborated-type-specifier (not a problem thus far). So we get to cp_parser_nested_name_specifier_opt which has a loop that breaks if we don't see a < or ::, but that means we can -- tentatively -- parse even B<U> which is not a nested-name-specifier (it doesn't end with a ::). Even though we're parsing B<U> tentatively, we issue an error in cp_parser_class_name -> make_typename_type, but here we should not. In fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the cp_parser_class_name hunk. I think this should compile because [temp.names]/4 says: "In a qualified-id used as the name in a typename-specifier, elaborated-type-specifier, using-declaration, or class-or-decltype, an optional keyword template appearing at the top level is ignored.", added in DR 1710. Also see DR 1812. This issue on its own is not a significant problem or a regression. However, in C++20, the typename here becomes optional, and so this test is rejected in C++20, but accepted in C++17: template <typename T> class A { template <typename U> class B { void fn(A<T>::B<U>); }; }; Here we morph A<T>::B<U> into a typename-specifier, but that happens in cp_parser_simple_type_specifier and we never handle it as above. To fake the template keyword I'm afraid we need to use cp_parser_template_id with template_keyword_p=true as in the patch below. The tricky thing is to avoid breaking concepts. DR 1710 PR c++/94057 - template keyword in a typename-specifier. * parser.c (cp_parser_simple_type_specifier): Assume that a < following a qualified-id in a typename-specifier begins a template argument list. (cp_parser_class_name): Complain only if not parsing tentatively. * g++.dg/template/dependent-name5.C: Update dg-error. * g++.dg/template/dependent-name7.C: New test. * g++.dg/template/dependent-name8.C: New test. * g++.dg/template/dependent-name9.C: New test. * g++.dg/template/dependent-name10.C: New test. * g++.dg/template/dependent-name11.C: New test. * g++.dg/template/dr1794.C: New test. * g++.dg/template/dr314.C: New test. * g++.dg/template/dr1710.C: New test. * g++.dg/template/dr1710-2.C: New test. --- gcc/cp/parser.c | 32 +++++++++++++++++-- .../g++.dg/template/dependent-name10.C | 18 +++++++++++ .../g++.dg/template/dependent-name11.C | 15 +++++++++ .../g++.dg/template/dependent-name5.C | 2 -- .../g++.dg/template/dependent-name7.C | 9 ++++++ .../g++.dg/template/dependent-name8.C | 9 ++++++ .../g++.dg/template/dependent-name9.C | 9 ++++++ gcc/testsuite/g++.dg/template/dr1710-2.C | 10 ++++++ gcc/testsuite/g++.dg/template/dr1710.C | 4 +++ gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++++++ gcc/testsuite/g++.dg/template/dr314.C | 15 +++++++++ 11 files changed, 133 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C create mode 100644 gcc/testsuite/g++.dg/template/dr314.C diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index cbd5510a8fb..f4175955992 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -18113,6 +18113,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, } } } + /* DR 1812: A < following a qualified-id in a typename-specifier + could safely be assumed to begin a template argument list, so + the template keyword should be optional. */ + else if (parser->scope + && qualified_p + && typename_p + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) + { + cp_parser_parse_tentatively (parser); + + type = cp_parser_template_id (parser, + /*template_keyword_p=*/true, + /*check_dependency_p=*/true, + none_type, + /*is_declaration=*/false); + /* This is handled below, so back off. */ + if (type && concept_check_p (type)) + cp_parser_simulate_error (parser); + + if (!cp_parser_parse_definitely (parser)) + type = NULL_TREE; + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) + type = make_typename_type (parser->scope, type, typename_type, + /*complain=*/tf_error); + else if (TREE_CODE (type) != TYPE_DECL) + type = NULL_TREE; + } /* Otherwise, look for a type-name. */ if (!type) @@ -23636,8 +23663,9 @@ cp_parser_class_name (cp_parser *parser, && decl != error_mark_node && !is_overloaded_fn (decl)) { - decl = make_typename_type (scope, decl, typename_type, - /*complain=*/tf_error); + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) + ? tf_none : tf_error); + decl = make_typename_type (scope, decl, typename_type, complain); if (decl != error_mark_node) decl = TYPE_NAME (decl); } diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C new file mode 100644 index 00000000000..18e024f7e6d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C @@ -0,0 +1,18 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> struct B { + typedef int TT; + typedef int TT2; + typedef int TT3; + typedef int TT4; + }; +}; + +struct X : A<int>::B<int> { + using A<int>::template B<int>::TT; + using typename A<int>::template B<int>::TT2; + using A<int>::B<int>::TT3; + using typename A<int>::B<int>::TT4; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C new file mode 100644 index 00000000000..687a9bd5df5 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C @@ -0,0 +1,15 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> + struct W { }; +}; + +void +g () +{ + // class-key nested-name-specifier template[opt] simple-template-id + struct A<int>::W<int> w; + struct A<int>::template W<int> w2; +} diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C index fc78983324b..15c1acb0347 100644 --- a/gcc/testsuite/g++.dg/template/dependent-name5.C +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C @@ -22,9 +22,7 @@ struct A typedef N<int> type6; typedef A::N<int> type7; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T>::N<int> type8; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } typedef typename A<T*>::template N<int> type10; diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C new file mode 100644 index 00000000000..3dfa42d2df0 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(A<T>::B<U>&); + void fn(A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C new file mode 100644 index 00000000000..ad9e44f9b85 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::B<U>&); + void fn(typename A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C new file mode 100644 index 00000000000..6dfdbc176c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::template B<U>&); + void fn(typename A<T>::template B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C new file mode 100644 index 00000000000..99d49b746b2 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C @@ -0,0 +1,10 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + }; +}; + +template<typename T> struct D : A<int>::B<int> {}; +template<typename T> struct D2 : A<int>::template B<int> {}; diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C new file mode 100644 index 00000000000..fbbccde9bbf --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710.C @@ -0,0 +1,4 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct D : T::template B<int>::template C<int> {}; diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C new file mode 100644 index 00000000000..f629d7d0b98 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1794.C @@ -0,0 +1,14 @@ +// DR 1794 - template keyword and alias templates. +// { dg-do compile { target c++11 } } + +template<template<typename> class Template> +struct Internal { + template<typename Arg> + using Bind = Template<Arg>; +}; + +template<template<typename> class Template, typename Arg> +using Instantiate = Template<Arg>; + +template<template<typename> class Template, typename Argument> +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C new file mode 100644 index 00000000000..7c0d8ac592f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr314.C @@ -0,0 +1,15 @@ +// DR 314 - template in base class specifier. + +template <typename T> +struct A { + template <typename U> + struct B {}; +}; + +template <typename T> +struct C : public A<T>::template B<T> { +}; + +template <typename T> +struct C2 : public A<int>::B<T> { +}; base-commit: 72b3bc895f023bf451357659cfe96c966945bdf9
On 3/20/20 7:02 PM, Marek Polacek wrote: > On Fri, Mar 20, 2020 at 02:12:49PM -0400, Jason Merrill wrote: >> On 3/20/20 1:06 PM, Marek Polacek wrote: >>> Wonderful. I've added a bunch of tests, and some from the related DRs too. >>> But I had a problem with the class-or-decltype case: if we have >>> >>> template<typename T> struct D : T::template B<int>::template C<int> {}; >>> >>> then we still require all the 'template' keywords here (as does clang). So I'm >>> kind of confused, but I don't think it's a big deal right now. >> >> This seems related enough that I'd like to fix it at the same time; why >> doesn't your patch fix it? Is it because typename_p is false? > > Ah, I was mistaken. Of course we need the template keyword here: it's a member of an > unknown specialization! That's why it's needed in contexts where we don't know whether or not we're naming a type. But where we do know that, as in a base-specifier, it isn't necessary. This is exactly DR 1710: "The keyword template is optional in a ... class-or-decltype (Clause 11.7 [class.derived])...." Jason
On Mon, Mar 23, 2020 at 10:41:28AM -0400, Jason Merrill wrote: > On 3/20/20 7:02 PM, Marek Polacek wrote: > > On Fri, Mar 20, 2020 at 02:12:49PM -0400, Jason Merrill wrote: > > > On 3/20/20 1:06 PM, Marek Polacek wrote: > > > > Wonderful. I've added a bunch of tests, and some from the related DRs too. > > > > But I had a problem with the class-or-decltype case: if we have > > > > > > > > template<typename T> struct D : T::template B<int>::template C<int> {}; > > > > > > > > then we still require all the 'template' keywords here (as does clang). So I'm > > > > kind of confused, but I don't think it's a big deal right now. > > > > > > This seems related enough that I'd like to fix it at the same time; why > > > doesn't your patch fix it? Is it because typename_p is false? > > > > Ah, I was mistaken. Of course we need the template keyword here: it's a member of an > > unknown specialization! > > That's why it's needed in contexts where we don't know whether or not we're > naming a type. But where we do know that, as in a base-specifier, it isn't > necessary. This is exactly DR 1710: "The keyword template is optional in a > ... class-or-decltype (Clause 11.7 [class.derived])...." Duh, not sure what I was thinking. I've implemented that in cp_parser_nested_name_specifier_opt: assume 'template' if we've seen 'typename'. If it turns out that this is wrong because it triggers in contexts where it shouldn't, we'll have to introduce something like CP_PARSER_FLAGS_TEMPLATE_OPTIONAL. With this another problem revealed: we weren't accepting an alias template after 'template' which DR1710 says is valid. Fixed by the TYPE_ALIAS_P hunk in the new check_template_keyword_in_nested_name_spec. (alias-decl1.C) But this is still not over: I noticed that template <typename T> struct S { template <typename TT> using U = TT; }; template <typename T> typename S<int>::template U<T>::type foo; is still rejected and shouldn't be. Here check_template_keyword_in_nested_name_spec gets <template_type_parm 0x7fffeaa42690 U type_0 VOID align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type 0x7fffeaa420a8 index 0 level 1 orig_level 2 chain <type_decl 0x7fffea90bda8 TT>> Any suggestions how to handle this? FWIW, bootstrapped/regtested on x86_64-linux. -- >8 -- Consider template <typename T> class A { template <typename U> class B { void fn(typename A<T>::B<U>); }; }; which is rejected with error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type whereas clang/icc/msvc accept it. "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments don't mention it anywhere, because the typename-specifier wasn't in C++11; it was only added to the language in N1376. Instead, we handle it as an elaborated-type-specifier (not a problem thus far). So we get to cp_parser_nested_name_specifier_opt which has a loop that breaks if we don't see a < or ::, but that means we can -- tentatively -- parse even B<U> which is not a nested-name-specifier (it doesn't end with a ::). Even though we're parsing B<U> tentatively, we issue an error in cp_parser_class_name -> make_typename_type, but here we should not. In fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the cp_parser_class_name hunk. I think this should compile because [temp.names]/4 says: "In a qualified-id used as the name in a typename-specifier, elaborated-type-specifier, using-declaration, or class-or-decltype, an optional keyword template appearing at the top level is ignored.", added in DR 1710. Also see DR 1812. This issue on its own is not a significant problem or a regression. However, in C++20, the typename here becomes optional, and so this test is rejected in C++20, but accepted in C++17: template <typename T> class A { template <typename U> class B { void fn(A<T>::B<U>); }; }; Here we morph A<T>::B<U> into a typename-specifier, but that happens in cp_parser_simple_type_specifier and we never handle it as above. To fake the template keyword I'm afraid we need to use cp_parser_template_id with template_keyword_p=true as in the patch below. The tricky thing is to avoid breaking concepts. To handle DR 1710, I made cp_parser_nested_name_specifier_opt assume that when we're naming a type, the template keyword is present, too. That revealed a bug: DR 1710 also says that the template keyword can be followed by an alias template, but we weren't prepared to handle that. alias-decl1.C exercise this. DR 1710 PR c++/94057 - template keyword in a typename-specifier. * parser.c (check_template_keyword_in_nested_name_spec): New. (cp_parser_nested_name_specifier_opt): Implement DR1710, optional 'template'. Call check_template_keyword_in_nested_name_spec. (cp_parser_simple_type_specifier): Assume that a < following a qualified-id in a typename-specifier begins a template argument list. (cp_parser_class_name): Complain only if not parsing tentatively. * g++.dg/cpp1y/alias-decl1.C: New test. * g++.dg/parse/missing-template1.C: Update dg-error. * g++.dg/parse/template3.C: Likewise. * g++.dg/template/error4.C: Likewise. * g++.dg/template/meminit2.C: Likewise. * g++.dg/template/dependent-name5.C: Likewise. * g++.dg/template/dependent-name7.C: New test. * g++.dg/template/dependent-name8.C: New test. * g++.dg/template/dependent-name9.C: New test. * g++.dg/template/dependent-name10.C: New test. * g++.dg/template/dependent-name11.C: New test. * g++.dg/template/dependent-name12.C: New test. * g++.dg/template/dependent-name13.C: New test. * g++.dg/template/dr1794.C: New test. * g++.dg/template/dr314.C: New test. * g++.dg/template/dr1710.C: New test. * g++.dg/template/dr1710-2.C: New test. * g++.old-deja/g++.pt/crash38.C: Update dg-error. --- gcc/cp/parser.c | 91 ++++++++++++++++--- gcc/testsuite/g++.dg/cpp1y/alias-decl1.C | 9 ++ .../g++.dg/parse/missing-template1.C | 4 +- gcc/testsuite/g++.dg/parse/template3.C | 5 +- .../g++.dg/template/dependent-name10.C | 18 ++++ .../g++.dg/template/dependent-name11.C | 15 +++ .../g++.dg/template/dependent-name12.C | 7 ++ .../g++.dg/template/dependent-name13.C | 8 ++ .../g++.dg/template/dependent-name5.C | 2 - .../g++.dg/template/dependent-name7.C | 9 ++ .../g++.dg/template/dependent-name8.C | 9 ++ .../g++.dg/template/dependent-name9.C | 9 ++ gcc/testsuite/g++.dg/template/dr1710-2.C | 10 ++ gcc/testsuite/g++.dg/template/dr1710.C | 9 ++ gcc/testsuite/g++.dg/template/dr1794.C | 14 +++ gcc/testsuite/g++.dg/template/dr314.C | 15 +++ gcc/testsuite/g++.dg/template/error4.C | 3 +- gcc/testsuite/g++.dg/template/meminit2.C | 4 +- gcc/testsuite/g++.old-deja/g++.pt/crash38.C | 6 +- 19 files changed, 214 insertions(+), 33 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl1.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name12.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name13.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C create mode 100644 gcc/testsuite/g++.dg/template/dr314.C diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index cbd5510a8fb..824fb18e83a 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -6266,6 +6266,39 @@ cp_parser_unqualified_id (cp_parser* parser, } } +/* Check [temp.names]/5: A name prefixed by the keyword template shall + be a template-id or the name shall refer to a class template or an + alias template. */ + +static void +check_template_keyword_in_nested_name_spec (tree name) +{ + if (CLASS_TYPE_P (name) + && ((CLASSTYPE_USE_TEMPLATE (name) + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) + || CLASSTYPE_IS_TEMPLATE (name))) + return; + + + if (TREE_CODE (name) == TYPENAME_TYPE) + { + if (TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) + return; + /* Alias templates are also OK. */ + else if (TYPE_ALIAS_P (name)) + { + tree tinfo = TYPE_ALIAS_TEMPLATE_INFO (name); + if (tinfo && DECL_ALIAS_TEMPLATE_P (TI_TEMPLATE (tinfo))) + return; + } + } + + permerror (input_location, TYPE_P (name) + ? G_("%qT is not a template") + : G_("%qD is not a template"), + name); +} + /* Parse an (optional) nested-name-specifier. nested-name-specifier: [C++98] @@ -6389,7 +6422,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, /* Look for the optional `template' keyword, if this isn't the first time through the loop. */ if (success) - template_keyword_p = cp_parser_optional_template_keyword (parser); + { + template_keyword_p = cp_parser_optional_template_keyword (parser); + /* DR1710: "In a qualified-id used as the name in + a typename-specifier, elaborated-type-specifier, using-declaration, + or class-or-decltype, an optional keyword template appearing at + the top level is ignored." */ + if (!template_keyword_p + && typename_keyword_p + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) + template_keyword_p = true; + } /* Save the old scope since the name lookup we are about to do might destroy it. */ @@ -6580,18 +6623,8 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, if (TREE_CODE (new_scope) == TYPE_DECL) new_scope = TREE_TYPE (new_scope); /* Uses of "template" must be followed by actual templates. */ - if (template_keyword_p - && !(CLASS_TYPE_P (new_scope) - && ((CLASSTYPE_USE_TEMPLATE (new_scope) - && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (new_scope))) - || CLASSTYPE_IS_TEMPLATE (new_scope))) - && !(TREE_CODE (new_scope) == TYPENAME_TYPE - && (TREE_CODE (TYPENAME_TYPE_FULLNAME (new_scope)) - == TEMPLATE_ID_EXPR))) - permerror (input_location, TYPE_P (new_scope) - ? G_("%qT is not a template") - : G_("%qD is not a template"), - new_scope); + if (template_keyword_p) + check_template_keyword_in_nested_name_spec (new_scope); /* If it is a class scope, try to complete it; we are about to be looking up names inside the class. */ if (TYPE_P (new_scope) @@ -18113,6 +18146,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, } } } + /* DR 1812: A < following a qualified-id in a typename-specifier + could safely be assumed to begin a template argument list, so + the template keyword should be optional. */ + else if (parser->scope + && qualified_p + && typename_p + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) + { + cp_parser_parse_tentatively (parser); + + type = cp_parser_template_id (parser, + /*template_keyword_p=*/true, + /*check_dependency_p=*/true, + none_type, + /*is_declaration=*/false); + /* This is handled below, so back off. */ + if (type && concept_check_p (type)) + cp_parser_simulate_error (parser); + + if (!cp_parser_parse_definitely (parser)) + type = NULL_TREE; + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) + type = make_typename_type (parser->scope, type, typename_type, + /*complain=*/tf_error); + else if (TREE_CODE (type) != TYPE_DECL) + type = NULL_TREE; + } /* Otherwise, look for a type-name. */ if (!type) @@ -23636,8 +23696,9 @@ cp_parser_class_name (cp_parser *parser, && decl != error_mark_node && !is_overloaded_fn (decl)) { - decl = make_typename_type (scope, decl, typename_type, - /*complain=*/tf_error); + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) + ? tf_none : tf_error); + decl = make_typename_type (scope, decl, typename_type, complain); if (decl != error_mark_node) decl = TYPE_NAME (decl); } diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C new file mode 100644 index 00000000000..e5397e71bd6 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile { target c++14 } } + +template <int> struct S { + template <int> struct A; + template <int N> using U = typename A<N>::foo; +}; +template <typename T> typename S<1>::U<T::foo>::type a; +template <typename T> typename S<1>::template U<T::foo>::type a2; diff --git a/gcc/testsuite/g++.dg/parse/missing-template1.C b/gcc/testsuite/g++.dg/parse/missing-template1.C index fcc3aa0c3ff..19c1433d09f 100644 --- a/gcc/testsuite/g++.dg/parse/missing-template1.C +++ b/gcc/testsuite/g++.dg/parse/missing-template1.C @@ -12,9 +12,7 @@ template <typename T> struct A template <typename T> void foo() { - typedef typename A<T>::B<T>::X Y; // { dg-error "non-template" "non" } - // { dg-error "not declare" "decl" { target *-*-* } .-1 } - // { dg-message "note" "note" { target *-*-* } .-2 } + typedef typename A<T>::B<T>::X Y; } void bar() diff --git a/gcc/testsuite/g++.dg/parse/template3.C b/gcc/testsuite/g++.dg/parse/template3.C index c284a5ee040..8da8a48a3c3 100644 --- a/gcc/testsuite/g++.dg/parse/template3.C +++ b/gcc/testsuite/g++.dg/parse/template3.C @@ -13,7 +13,4 @@ struct X : Outer<b>::template Inner<T> {}; template <bool b, typename T> -struct Y : Outer<b>::Inner<T> {}; // { dg-error "used as template" "temp" } -// { dg-error "expected" "exp" { target *-*-* } .-1 } -// { dg-message "note" "note" { target *-*-* } .-2 } - +struct Y : Outer<b>::Inner<T> {}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C new file mode 100644 index 00000000000..18e024f7e6d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C @@ -0,0 +1,18 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> struct B { + typedef int TT; + typedef int TT2; + typedef int TT3; + typedef int TT4; + }; +}; + +struct X : A<int>::B<int> { + using A<int>::template B<int>::TT; + using typename A<int>::template B<int>::TT2; + using A<int>::B<int>::TT3; + using typename A<int>::B<int>::TT4; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C new file mode 100644 index 00000000000..687a9bd5df5 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C @@ -0,0 +1,15 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> + struct W { }; +}; + +void +g () +{ + // class-key nested-name-specifier template[opt] simple-template-id + struct A<int>::W<int> w; + struct A<int>::template W<int> w2; +} diff --git a/gcc/testsuite/g++.dg/template/dependent-name12.C b/gcc/testsuite/g++.dg/template/dependent-name12.C new file mode 100644 index 00000000000..7ee94e7457d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name12.C @@ -0,0 +1,7 @@ +// PR c++/94057 - template keyword in a typename-specifier. + +template <bool> struct A; +template <typename, typename> struct B; +template <typename T, typename U, typename V> struct B<T U::*, V> { + typename A<V::x>::type::type t; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name13.C b/gcc/testsuite/g++.dg/template/dependent-name13.C new file mode 100644 index 00000000000..1e971168657 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name13.C @@ -0,0 +1,8 @@ +// DR 1710 - Missing template keyword in class-or-decltype + +template<typename T> struct S { + void fn(typename T::template B<int>::template C<int>); + void fn2(typename T::B<int>::template C<int>); + void fn3(typename T::template B<int>::C<int>); + void fn4(typename T::B<int>::C<int>); +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C index fc78983324b..15c1acb0347 100644 --- a/gcc/testsuite/g++.dg/template/dependent-name5.C +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C @@ -22,9 +22,7 @@ struct A typedef N<int> type6; typedef A::N<int> type7; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T>::N<int> type8; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } typedef typename A<T*>::template N<int> type10; diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C new file mode 100644 index 00000000000..3dfa42d2df0 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(A<T>::B<U>&); + void fn(A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C new file mode 100644 index 00000000000..ad9e44f9b85 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::B<U>&); + void fn(typename A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C new file mode 100644 index 00000000000..6dfdbc176c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::template B<U>&); + void fn(typename A<T>::template B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C new file mode 100644 index 00000000000..99d49b746b2 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C @@ -0,0 +1,10 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + }; +}; + +template<typename T> struct D : A<int>::B<int> {}; +template<typename T> struct D2 : A<int>::template B<int> {}; diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C new file mode 100644 index 00000000000..c945977971f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct D : T::template B<int>::template C<int> {}; +template<typename T> struct D2 : T::B<int>::template C<int> {}; +template<typename T> struct D3 : T::template B<int>::C<int> {}; +template<typename T> struct D4 : T::B<int>::C<int> {}; +template<typename T> struct D5 : T::template B<int>::type::type {}; +template<typename T> struct D6 : T::B<int>::type::type {}; diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C new file mode 100644 index 00000000000..f629d7d0b98 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1794.C @@ -0,0 +1,14 @@ +// DR 1794 - template keyword and alias templates. +// { dg-do compile { target c++11 } } + +template<template<typename> class Template> +struct Internal { + template<typename Arg> + using Bind = Template<Arg>; +}; + +template<template<typename> class Template, typename Arg> +using Instantiate = Template<Arg>; + +template<template<typename> class Template, typename Argument> +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C new file mode 100644 index 00000000000..7c0d8ac592f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr314.C @@ -0,0 +1,15 @@ +// DR 314 - template in base class specifier. + +template <typename T> +struct A { + template <typename U> + struct B {}; +}; + +template <typename T> +struct C : public A<T>::template B<T> { +}; + +template <typename T> +struct C2 : public A<int>::B<T> { +}; diff --git a/gcc/testsuite/g++.dg/template/error4.C b/gcc/testsuite/g++.dg/template/error4.C index 9d76561aa02..a5030f06c98 100644 --- a/gcc/testsuite/g++.dg/template/error4.C +++ b/gcc/testsuite/g++.dg/template/error4.C @@ -5,5 +5,4 @@ template<class T> struct C1 }; template<class T, class U> -void foo(typename C1<T>::C2<U>::Type *) { } // { dg-error "template" "error " } -// { dg-message "note" "note" { target *-*-* } .-1 } +void foo(typename C1<T>::C2<U>::Type *) { } diff --git a/gcc/testsuite/g++.dg/template/meminit2.C b/gcc/testsuite/g++.dg/template/meminit2.C index db6e0427fc7..6a56a806746 100644 --- a/gcc/testsuite/g++.dg/template/meminit2.C +++ b/gcc/testsuite/g++.dg/template/meminit2.C @@ -14,8 +14,6 @@ struct A : typename O<T>::template I<int> { // { dg-error "keyword 'typename' template <typename T> struct B : O<T>::template I<int> { - B() : O<T>::I<int>() // { dg-error "used as template|it is a template" } + B() : O<T>::I<int>() {} }; - -// { dg-bogus "end of input" "bogus token skipping in the parser" { xfail *-*-* } 17 } diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C index 5d386132436..60cd5e3f44e 100644 --- a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C +++ b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C @@ -3,10 +3,8 @@ template <class T> struct S { - typedef typename T::Y<T>::Z X; // { dg-error "non-template" "non-template" } No Y in A -// { dg-message "note" "note" { target *-*-* } .-1 } -// { dg-error "does not declare" "not declare" { target *-*-* } .-2 } - X x; // { dg-error "does not name a type" } No Y in A + typedef typename T::Y<T>::Z X; // { dg-error "not a class template" } No Y in A + X x; }; struct A { base-commit: c2211a60ff05b7a0289d3e287e72c181bb4d5d8b
On 3/24/20 11:45 AM, Marek Polacek wrote: > On Mon, Mar 23, 2020 at 10:41:28AM -0400, Jason Merrill wrote: >> On 3/20/20 7:02 PM, Marek Polacek wrote: >>> On Fri, Mar 20, 2020 at 02:12:49PM -0400, Jason Merrill wrote: >>>> On 3/20/20 1:06 PM, Marek Polacek wrote: >>>>> Wonderful. I've added a bunch of tests, and some from the related DRs too. >>>>> But I had a problem with the class-or-decltype case: if we have >>>>> >>>>> template<typename T> struct D : T::template B<int>::template C<int> {}; >>>>> >>>>> then we still require all the 'template' keywords here (as does clang). So I'm >>>>> kind of confused, but I don't think it's a big deal right now. >>>> >>>> This seems related enough that I'd like to fix it at the same time; why >>>> doesn't your patch fix it? Is it because typename_p is false? >>> >>> Ah, I was mistaken. Of course we need the template keyword here: it's a member of an >>> unknown specialization! >> >> That's why it's needed in contexts where we don't know whether or not we're >> naming a type. But where we do know that, as in a base-specifier, it isn't >> necessary. This is exactly DR 1710: "The keyword template is optional in a >> ... class-or-decltype (Clause 11.7 [class.derived])...." > > Duh, not sure what I was thinking. > > I've implemented that in cp_parser_nested_name_specifier_opt: assume 'template' > if we've seen 'typename'. If it turns out that this is wrong because it > triggers in contexts where it shouldn't, we'll have to introduce something like > CP_PARSER_FLAGS_TEMPLATE_OPTIONAL. > > With this another problem revealed: we weren't accepting an alias template > after 'template' which DR1710 says is valid. Fixed by the TYPE_ALIAS_P hunk > in the new check_template_keyword_in_nested_name_spec. (alias-decl1.C) > > But this is still not over: I noticed that > > template <typename T> struct S { > template <typename TT> > using U = TT; > }; > template <typename T> typename S<int>::template U<T>::type foo; > > is still rejected and shouldn't be. Here check_template_keyword_in_nested_name_spec > gets > > <template_type_parm 0x7fffeaa42690 U type_0 VOID > align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type 0x7fffeaa420a8 > index 0 level 1 orig_level 2 > chain <type_decl 0x7fffea90bda8 TT>> > > Any suggestions how to handle this? It should work to check for an alias whether or not the target is a TYPENAME_TYPE. > FWIW, bootstrapped/regtested on x86_64-linux. > > -- >8 -- > Consider > > template <typename T> class A { > template <typename U> class B { > void fn(typename A<T>::B<U>); > }; > }; > > which is rejected with > error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type > whereas clang/icc/msvc accept it. > > "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments > don't mention it anywhere, because the typename-specifier wasn't in C++11; > it was only added to the language in N1376. Instead, we handle it as > an elaborated-type-specifier (not a problem thus far). So we get to > cp_parser_nested_name_specifier_opt which has a loop that breaks if we > don't see a < or ::, but that means we can -- tentatively -- parse even > B<U> which is not a nested-name-specifier (it doesn't end with a ::). > > Even though we're parsing B<U> tentatively, we issue an error in > cp_parser_class_name -> make_typename_type, but here we should not. In > fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the > cp_parser_class_name hunk. > > I think this should compile because [temp.names]/4 says: "In a qualified-id > used as the name in a typename-specifier, elaborated-type-specifier, > using-declaration, or class-or-decltype, an optional keyword template > appearing at the top level is ignored.", added in DR 1710. Also see > DR 1812. > > This issue on its own is not a significant problem or a regression. > However, in C++20, the typename here becomes optional, and so this test > is rejected in C++20, but accepted in C++17: > > template <typename T> class A { > template <typename U> class B { > void fn(A<T>::B<U>); > }; > }; > > Here we morph A<T>::B<U> into a typename-specifier, but that happens > in cp_parser_simple_type_specifier and we never handle it as above. > To fake the template keyword I'm afraid we need to use cp_parser_template_id > with template_keyword_p=true as in the patch below. The tricky thing > is to avoid breaking concepts. > > To handle DR 1710, I made cp_parser_nested_name_specifier_opt assume that > when we're naming a type, the template keyword is present, too. That > revealed a bug: DR 1710 also says that the template keyword can be followed > by an alias template, but we weren't prepared to handle that. alias-decl1.C > exercise this. > > DR 1710 > PR c++/94057 - template keyword in a typename-specifier. > * parser.c (check_template_keyword_in_nested_name_spec): New. > (cp_parser_nested_name_specifier_opt): Implement DR1710, optional > 'template'. Call check_template_keyword_in_nested_name_spec. > (cp_parser_simple_type_specifier): Assume that a < > following a qualified-id in a typename-specifier begins > a template argument list. > (cp_parser_class_name): Complain only if not parsing tentatively. > > * g++.dg/cpp1y/alias-decl1.C: New test. > * g++.dg/parse/missing-template1.C: Update dg-error. > * g++.dg/parse/template3.C: Likewise. > * g++.dg/template/error4.C: Likewise. > * g++.dg/template/meminit2.C: Likewise. > * g++.dg/template/dependent-name5.C: Likewise. > * g++.dg/template/dependent-name7.C: New test. > * g++.dg/template/dependent-name8.C: New test. > * g++.dg/template/dependent-name9.C: New test. > * g++.dg/template/dependent-name10.C: New test. > * g++.dg/template/dependent-name11.C: New test. > * g++.dg/template/dependent-name12.C: New test. > * g++.dg/template/dependent-name13.C: New test. > * g++.dg/template/dr1794.C: New test. > * g++.dg/template/dr314.C: New test. > * g++.dg/template/dr1710.C: New test. > * g++.dg/template/dr1710-2.C: New test. > * g++.old-deja/g++.pt/crash38.C: Update dg-error. > --- > gcc/cp/parser.c | 91 ++++++++++++++++--- > gcc/testsuite/g++.dg/cpp1y/alias-decl1.C | 9 ++ > .../g++.dg/parse/missing-template1.C | 4 +- > gcc/testsuite/g++.dg/parse/template3.C | 5 +- > .../g++.dg/template/dependent-name10.C | 18 ++++ > .../g++.dg/template/dependent-name11.C | 15 +++ > .../g++.dg/template/dependent-name12.C | 7 ++ > .../g++.dg/template/dependent-name13.C | 8 ++ > .../g++.dg/template/dependent-name5.C | 2 - > .../g++.dg/template/dependent-name7.C | 9 ++ > .../g++.dg/template/dependent-name8.C | 9 ++ > .../g++.dg/template/dependent-name9.C | 9 ++ > gcc/testsuite/g++.dg/template/dr1710-2.C | 10 ++ > gcc/testsuite/g++.dg/template/dr1710.C | 9 ++ > gcc/testsuite/g++.dg/template/dr1794.C | 14 +++ > gcc/testsuite/g++.dg/template/dr314.C | 15 +++ > gcc/testsuite/g++.dg/template/error4.C | 3 +- > gcc/testsuite/g++.dg/template/meminit2.C | 4 +- > gcc/testsuite/g++.old-deja/g++.pt/crash38.C | 6 +- > 19 files changed, 214 insertions(+), 33 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name12.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name13.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C > create mode 100644 gcc/testsuite/g++.dg/template/dr314.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index cbd5510a8fb..824fb18e83a 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -6266,6 +6266,39 @@ cp_parser_unqualified_id (cp_parser* parser, > } > } > > +/* Check [temp.names]/5: A name prefixed by the keyword template shall > + be a template-id or the name shall refer to a class template or an > + alias template. */ > + > +static void > +check_template_keyword_in_nested_name_spec (tree name) > +{ > + if (CLASS_TYPE_P (name) > + && ((CLASSTYPE_USE_TEMPLATE (name) > + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) > + || CLASSTYPE_IS_TEMPLATE (name))) > + return; > + > + > + if (TREE_CODE (name) == TYPENAME_TYPE) > + { > + if (TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) > + return; > + /* Alias templates are also OK. */ > + else if (TYPE_ALIAS_P (name)) > + { > + tree tinfo = TYPE_ALIAS_TEMPLATE_INFO (name); > + if (tinfo && DECL_ALIAS_TEMPLATE_P (TI_TEMPLATE (tinfo))) > + return; > + } > + } I think you want to check all typedefs like in e.g. find_parameter_packs_r; if the name is a typedef, it's only suitable if alias_template_specialization_p. > + permerror (input_location, TYPE_P (name) > + ? G_("%qT is not a template") > + : G_("%qD is not a template"), > + name); > +} > + > /* Parse an (optional) nested-name-specifier. > > nested-name-specifier: [C++98] > @@ -6389,7 +6422,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > /* Look for the optional `template' keyword, if this isn't the > first time through the loop. */ > if (success) > - template_keyword_p = cp_parser_optional_template_keyword (parser); > + { > + template_keyword_p = cp_parser_optional_template_keyword (parser); > + /* DR1710: "In a qualified-id used as the name in > + a typename-specifier, elaborated-type-specifier, using-declaration, > + or class-or-decltype, an optional keyword template appearing at > + the top level is ignored." */ > + if (!template_keyword_p > + && typename_keyword_p > + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) > + template_keyword_p = true; > + } > > /* Save the old scope since the name lookup we are about to do > might destroy it. */ > @@ -6580,18 +6623,8 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > if (TREE_CODE (new_scope) == TYPE_DECL) > new_scope = TREE_TYPE (new_scope); > /* Uses of "template" must be followed by actual templates. */ > - if (template_keyword_p > - && !(CLASS_TYPE_P (new_scope) > - && ((CLASSTYPE_USE_TEMPLATE (new_scope) > - && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (new_scope))) > - || CLASSTYPE_IS_TEMPLATE (new_scope))) > - && !(TREE_CODE (new_scope) == TYPENAME_TYPE > - && (TREE_CODE (TYPENAME_TYPE_FULLNAME (new_scope)) > - == TEMPLATE_ID_EXPR))) > - permerror (input_location, TYPE_P (new_scope) > - ? G_("%qT is not a template") > - : G_("%qD is not a template"), > - new_scope); > + if (template_keyword_p) > + check_template_keyword_in_nested_name_spec (new_scope); > /* If it is a class scope, try to complete it; we are about to > be looking up names inside the class. */ > if (TYPE_P (new_scope) > @@ -18113,6 +18146,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, > } > } > } > + /* DR 1812: A < following a qualified-id in a typename-specifier > + could safely be assumed to begin a template argument list, so > + the template keyword should be optional. */ > + else if (parser->scope > + && qualified_p > + && typename_p > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) > + { > + cp_parser_parse_tentatively (parser); > + > + type = cp_parser_template_id (parser, > + /*template_keyword_p=*/true, > + /*check_dependency_p=*/true, > + none_type, > + /*is_declaration=*/false); > + /* This is handled below, so back off. */ > + if (type && concept_check_p (type)) > + cp_parser_simulate_error (parser); > + > + if (!cp_parser_parse_definitely (parser)) > + type = NULL_TREE; > + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) > + type = make_typename_type (parser->scope, type, typename_type, > + /*complain=*/tf_error); > + else if (TREE_CODE (type) != TYPE_DECL) > + type = NULL_TREE; > + } > > /* Otherwise, look for a type-name. */ > if (!type) > @@ -23636,8 +23696,9 @@ cp_parser_class_name (cp_parser *parser, > && decl != error_mark_node > && !is_overloaded_fn (decl)) > { > - decl = make_typename_type (scope, decl, typename_type, > - /*complain=*/tf_error); > + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) > + ? tf_none : tf_error); > + decl = make_typename_type (scope, decl, typename_type, complain); Why? > if (decl != error_mark_node) > decl = TYPE_NAME (decl); > } > diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > new file mode 100644 > index 00000000000..e5397e71bd6 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile { target c++14 } } > + > +template <int> struct S { > + template <int> struct A; > + template <int N> using U = typename A<N>::foo; > +}; > +template <typename T> typename S<1>::U<T::foo>::type a; > +template <typename T> typename S<1>::template U<T::foo>::type a2; > diff --git a/gcc/testsuite/g++.dg/parse/missing-template1.C b/gcc/testsuite/g++.dg/parse/missing-template1.C > index fcc3aa0c3ff..19c1433d09f 100644 > --- a/gcc/testsuite/g++.dg/parse/missing-template1.C > +++ b/gcc/testsuite/g++.dg/parse/missing-template1.C > @@ -12,9 +12,7 @@ template <typename T> struct A > > template <typename T> void foo() > { > - typedef typename A<T>::B<T>::X Y; // { dg-error "non-template" "non" } > - // { dg-error "not declare" "decl" { target *-*-* } .-1 } > - // { dg-message "note" "note" { target *-*-* } .-2 } > + typedef typename A<T>::B<T>::X Y; > } > > void bar() > diff --git a/gcc/testsuite/g++.dg/parse/template3.C b/gcc/testsuite/g++.dg/parse/template3.C > index c284a5ee040..8da8a48a3c3 100644 > --- a/gcc/testsuite/g++.dg/parse/template3.C > +++ b/gcc/testsuite/g++.dg/parse/template3.C > @@ -13,7 +13,4 @@ struct X : Outer<b>::template Inner<T> > {}; > > template <bool b, typename T> > -struct Y : Outer<b>::Inner<T> {}; // { dg-error "used as template" "temp" } > -// { dg-error "expected" "exp" { target *-*-* } .-1 } > -// { dg-message "note" "note" { target *-*-* } .-2 } > - > +struct Y : Outer<b>::Inner<T> {}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C > new file mode 100644 > index 00000000000..18e024f7e6d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C > @@ -0,0 +1,18 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> struct B { > + typedef int TT; > + typedef int TT2; > + typedef int TT3; > + typedef int TT4; > + }; > +}; > + > +struct X : A<int>::B<int> { > + using A<int>::template B<int>::TT; > + using typename A<int>::template B<int>::TT2; > + using A<int>::B<int>::TT3; > + using typename A<int>::B<int>::TT4; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C > new file mode 100644 > index 00000000000..687a9bd5df5 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C > @@ -0,0 +1,15 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> > + struct W { }; > +}; > + > +void > +g () > +{ > + // class-key nested-name-specifier template[opt] simple-template-id > + struct A<int>::W<int> w; > + struct A<int>::template W<int> w2; > +} > diff --git a/gcc/testsuite/g++.dg/template/dependent-name12.C b/gcc/testsuite/g++.dg/template/dependent-name12.C > new file mode 100644 > index 00000000000..7ee94e7457d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name12.C > @@ -0,0 +1,7 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > + > +template <bool> struct A; > +template <typename, typename> struct B; > +template <typename T, typename U, typename V> struct B<T U::*, V> { > + typename A<V::x>::type::type t; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name13.C b/gcc/testsuite/g++.dg/template/dependent-name13.C > new file mode 100644 > index 00000000000..1e971168657 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name13.C > @@ -0,0 +1,8 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > + > +template<typename T> struct S { > + void fn(typename T::template B<int>::template C<int>); > + void fn2(typename T::B<int>::template C<int>); > + void fn3(typename T::template B<int>::C<int>); > + void fn4(typename T::B<int>::C<int>); > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C > index fc78983324b..15c1acb0347 100644 > --- a/gcc/testsuite/g++.dg/template/dependent-name5.C > +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C > @@ -22,9 +22,7 @@ struct A > > typedef N<int> type6; > typedef A::N<int> type7; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T>::N<int> type8; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } > typedef typename A<T*>::template N<int> type10; > > diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C > new file mode 100644 > index 00000000000..3dfa42d2df0 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(A<T>::B<U>&); > + void fn(A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C > new file mode 100644 > index 00000000000..ad9e44f9b85 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::B<U>&); > + void fn(typename A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C > new file mode 100644 > index 00000000000..6dfdbc176c1 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::template B<U>&); > + void fn(typename A<T>::template B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C > new file mode 100644 > index 00000000000..99d49b746b2 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C > @@ -0,0 +1,10 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + }; > +}; > + > +template<typename T> struct D : A<int>::B<int> {}; > +template<typename T> struct D2 : A<int>::template B<int> {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C > new file mode 100644 > index 00000000000..c945977971f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct D : T::template B<int>::template C<int> {}; > +template<typename T> struct D2 : T::B<int>::template C<int> {}; > +template<typename T> struct D3 : T::template B<int>::C<int> {}; > +template<typename T> struct D4 : T::B<int>::C<int> {}; > +template<typename T> struct D5 : T::template B<int>::type::type {}; > +template<typename T> struct D6 : T::B<int>::type::type {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C > new file mode 100644 > index 00000000000..f629d7d0b98 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1794.C > @@ -0,0 +1,14 @@ > +// DR 1794 - template keyword and alias templates. > +// { dg-do compile { target c++11 } } > + > +template<template<typename> class Template> > +struct Internal { > + template<typename Arg> > + using Bind = Template<Arg>; > +}; > + > +template<template<typename> class Template, typename Arg> > +using Instantiate = Template<Arg>; > + > +template<template<typename> class Template, typename Argument> > +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; > diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C > new file mode 100644 > index 00000000000..7c0d8ac592f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr314.C > @@ -0,0 +1,15 @@ > +// DR 314 - template in base class specifier. > + > +template <typename T> > +struct A { > + template <typename U> > + struct B {}; > +}; > + > +template <typename T> > +struct C : public A<T>::template B<T> { > +}; > + > +template <typename T> > +struct C2 : public A<int>::B<T> { > +}; > diff --git a/gcc/testsuite/g++.dg/template/error4.C b/gcc/testsuite/g++.dg/template/error4.C > index 9d76561aa02..a5030f06c98 100644 > --- a/gcc/testsuite/g++.dg/template/error4.C > +++ b/gcc/testsuite/g++.dg/template/error4.C > @@ -5,5 +5,4 @@ template<class T> struct C1 > }; > > template<class T, class U> > -void foo(typename C1<T>::C2<U>::Type *) { } // { dg-error "template" "error " } > -// { dg-message "note" "note" { target *-*-* } .-1 } > +void foo(typename C1<T>::C2<U>::Type *) { } > diff --git a/gcc/testsuite/g++.dg/template/meminit2.C b/gcc/testsuite/g++.dg/template/meminit2.C > index db6e0427fc7..6a56a806746 100644 > --- a/gcc/testsuite/g++.dg/template/meminit2.C > +++ b/gcc/testsuite/g++.dg/template/meminit2.C > @@ -14,8 +14,6 @@ struct A : typename O<T>::template I<int> { // { dg-error "keyword 'typename' > > template <typename T> > struct B : O<T>::template I<int> { > - B() : O<T>::I<int>() // { dg-error "used as template|it is a template" } > + B() : O<T>::I<int>() > {} > }; > - > -// { dg-bogus "end of input" "bogus token skipping in the parser" { xfail *-*-* } 17 } > diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > index 5d386132436..60cd5e3f44e 100644 > --- a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > +++ b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > @@ -3,10 +3,8 @@ > > template <class T> > struct S { > - typedef typename T::Y<T>::Z X; // { dg-error "non-template" "non-template" } No Y in A > -// { dg-message "note" "note" { target *-*-* } .-1 } > -// { dg-error "does not declare" "not declare" { target *-*-* } .-2 } > - X x; // { dg-error "does not name a type" } No Y in A > + typedef typename T::Y<T>::Z X; // { dg-error "not a class template" } No Y in A > + X x; > }; > > struct A { > > base-commit: c2211a60ff05b7a0289d3e287e72c181bb4d5d8b >
On Wed, Mar 25, 2020 at 12:00:24AM -0400, Jason Merrill wrote: > On 3/24/20 11:45 AM, Marek Polacek wrote: > > On Mon, Mar 23, 2020 at 10:41:28AM -0400, Jason Merrill wrote: > > > On 3/20/20 7:02 PM, Marek Polacek wrote: > > > > On Fri, Mar 20, 2020 at 02:12:49PM -0400, Jason Merrill wrote: > > > > > On 3/20/20 1:06 PM, Marek Polacek wrote: > > > > > > Wonderful. I've added a bunch of tests, and some from the related DRs too. > > > > > > But I had a problem with the class-or-decltype case: if we have > > > > > > > > > > > > template<typename T> struct D : T::template B<int>::template C<int> {}; > > > > > > > > > > > > then we still require all the 'template' keywords here (as does clang). So I'm > > > > > > kind of confused, but I don't think it's a big deal right now. > > > > > > > > > > This seems related enough that I'd like to fix it at the same time; why > > > > > doesn't your patch fix it? Is it because typename_p is false? > > > > > > > > Ah, I was mistaken. Of course we need the template keyword here: it's a member of an > > > > unknown specialization! > > > > > > That's why it's needed in contexts where we don't know whether or not we're > > > naming a type. But where we do know that, as in a base-specifier, it isn't > > > necessary. This is exactly DR 1710: "The keyword template is optional in a > > > ... class-or-decltype (Clause 11.7 [class.derived])...." > > > > Duh, not sure what I was thinking. > > > > I've implemented that in cp_parser_nested_name_specifier_opt: assume 'template' > > if we've seen 'typename'. If it turns out that this is wrong because it > > triggers in contexts where it shouldn't, we'll have to introduce something like > > CP_PARSER_FLAGS_TEMPLATE_OPTIONAL. > > > > With this another problem revealed: we weren't accepting an alias template > > after 'template' which DR1710 says is valid. Fixed by the TYPE_ALIAS_P hunk > > in the new check_template_keyword_in_nested_name_spec. (alias-decl1.C) > > > > But this is still not over: I noticed that > > > > template <typename T> struct S { > > template <typename TT> > > using U = TT; > > }; > > template <typename T> typename S<int>::template U<T>::type foo; > > > > is still rejected and shouldn't be. Here check_template_keyword_in_nested_name_spec > > gets > > > > <template_type_parm 0x7fffeaa42690 U type_0 VOID > > align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type 0x7fffeaa420a8 > > index 0 level 1 orig_level 2 > > chain <type_decl 0x7fffea90bda8 TT>> > > > > Any suggestions how to handle this? > > It should work to check for an alias whether or not the target is a > TYPENAME_TYPE. Hmm, we don't have a TYPENAME_TYPE here at all, but since that template_type_parm is typedef_variant_p, it can be handled along with... > > +static void > > +check_template_keyword_in_nested_name_spec (tree name) > > +{ > > + if (CLASS_TYPE_P (name) > > + && ((CLASSTYPE_USE_TEMPLATE (name) > > + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) > > + || CLASSTYPE_IS_TEMPLATE (name))) > > + return; > > + > > + > > + if (TREE_CODE (name) == TYPENAME_TYPE) > > + { > > + if (TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) > > + return; > > + /* Alias templates are also OK. */ > > + else if (TYPE_ALIAS_P (name)) > > + { > > + tree tinfo = TYPE_ALIAS_TEMPLATE_INFO (name); > > + if (tinfo && DECL_ALIAS_TEMPLATE_P (TI_TEMPLATE (tinfo))) > > + return; > > + } > > + } > > I think you want to check all typedefs like in e.g. find_parameter_packs_r; > if the name is a typedef, it's only suitable if > alias_template_specialization_p. ..this: Since alias_template_specialization_p already checks TYPE_P and typedef_variant_p, can we simply use that? > > /* Parse an (optional) nested-name-specifier. > > nested-name-specifier: [C++98] > > @@ -6389,7 +6422,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > > /* Look for the optional `template' keyword, if this isn't the > > first time through the loop. */ > > if (success) > > - template_keyword_p = cp_parser_optional_template_keyword (parser); > > + { > > + template_keyword_p = cp_parser_optional_template_keyword (parser); > > + /* DR1710: "In a qualified-id used as the name in > > + a typename-specifier, elaborated-type-specifier, using-declaration, > > + or class-or-decltype, an optional keyword template appearing at > > + the top level is ignored." */ > > + if (!template_keyword_p > > + && typename_keyword_p > > + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) > > + template_keyword_p = true; > > + } And since we now do this, we don't need... > > @@ -23636,8 +23696,9 @@ cp_parser_class_name (cp_parser *parser, > > && decl != error_mark_node > > && !is_overloaded_fn (decl)) > > { > > - decl = make_typename_type (scope, decl, typename_type, > > - /*complain=*/tf_error); > > + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) > > + ? tf_none : tf_error); > > + decl = make_typename_type (scope, decl, typename_type, complain); > > Why? ...this hunk, so dropped. New test alias-decl2.C added, otherwise no changes. Bootstrapped/regtested on x86_64-linux, ok for trunk? -- >8 -- Consider template <typename T> class A { template <typename U> class B { void fn(typename A<T>::B<U>); }; }; which is rejected with error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type whereas clang/icc/msvc accept it. "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments don't mention it anywhere, because the typename-specifier wasn't in C++11; it was only added to the language in N1376. Instead, we handle it as an elaborated-type-specifier (not a problem thus far). So we get to cp_parser_nested_name_specifier_opt which has a loop that breaks if we don't see a < or ::, but that means we can -- tentatively -- parse even B<U> which is not a nested-name-specifier (it doesn't end with a ::). I think this should compile because [temp.names]/4 says: "In a qualified-id used as the name in a typename-specifier, elaborated-type-specifier, using-declaration, or class-or-decltype, an optional keyword template appearing at the top level is ignored.", added in DR 1710. Also see DR 1812. This issue on its own is not a significant problem or a regression. However, in C++20, the typename here becomes optional, and so this test is rejected in C++20, but accepted in C++17: template <typename T> class A { template <typename U> class B { void fn(A<T>::B<U>); }; }; Here we morph A<T>::B<U> into a typename-specifier, but that happens in cp_parser_simple_type_specifier and we never handle it as above. To fake the template keyword I'm afraid we need to use cp_parser_template_id with template_keyword_p=true as in the patch below. The tricky thing is to avoid breaking concepts. To handle DR 1710, I made cp_parser_nested_name_specifier_opt assume that when we're naming a type, the template keyword is present, too. That revealed a bug: DR 1710 also says that the template keyword can be followed by an alias template, but we weren't prepared to handle that. alias-decl?.C exercise this. DR 1710 PR c++/94057 - template keyword in a typename-specifier. * parser.c (check_template_keyword_in_nested_name_spec): New. (cp_parser_nested_name_specifier_opt): Implement DR1710, optional 'template'. Call check_template_keyword_in_nested_name_spec. (cp_parser_simple_type_specifier): Assume that a < following a qualified-id in a typename-specifier begins a template argument list. * g++.dg/cpp1y/alias-decl1.C: New test. * g++.dg/cpp1y/alias-decl2.C: New test. * g++.dg/parse/missing-template1.C: Update dg-error. * g++.dg/parse/template3.C: Likewise. * g++.dg/template/error4.C: Likewise. * g++.dg/template/meminit2.C: Likewise. * g++.dg/template/dependent-name5.C: Likewise. * g++.dg/template/dependent-name7.C: New test. * g++.dg/template/dependent-name8.C: New test. * g++.dg/template/dependent-name9.C: New test. * g++.dg/template/dependent-name10.C: New test. * g++.dg/template/dependent-name11.C: New test. * g++.dg/template/dependent-name12.C: New test. * g++.dg/template/dependent-name13.C: New test. * g++.dg/template/dr1794.C: New test. * g++.dg/template/dr314.C: New test. * g++.dg/template/dr1710.C: New test. * g++.dg/template/dr1710-2.C: New test. * g++.old-deja/g++.pt/crash38.C: Update dg-error. --- gcc/cp/parser.c | 79 ++++++++++++++++--- gcc/testsuite/g++.dg/cpp1y/alias-decl1.C | 9 +++ gcc/testsuite/g++.dg/cpp1y/alias-decl2.C | 8 ++ .../g++.dg/parse/missing-template1.C | 4 +- gcc/testsuite/g++.dg/parse/template3.C | 5 +- .../g++.dg/template/dependent-name10.C | 18 +++++ .../g++.dg/template/dependent-name11.C | 15 ++++ .../g++.dg/template/dependent-name12.C | 7 ++ .../g++.dg/template/dependent-name13.C | 8 ++ .../g++.dg/template/dependent-name5.C | 2 - .../g++.dg/template/dependent-name7.C | 9 +++ .../g++.dg/template/dependent-name8.C | 9 +++ .../g++.dg/template/dependent-name9.C | 9 +++ gcc/testsuite/g++.dg/template/dr1710-2.C | 10 +++ gcc/testsuite/g++.dg/template/dr1710.C | 9 +++ gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++ gcc/testsuite/g++.dg/template/dr314.C | 15 ++++ gcc/testsuite/g++.dg/template/error4.C | 3 +- gcc/testsuite/g++.dg/template/meminit2.C | 4 +- gcc/testsuite/g++.old-deja/g++.pt/crash38.C | 6 +- 20 files changed, 212 insertions(+), 31 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl1.C create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl2.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name12.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name13.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C create mode 100644 gcc/testsuite/g++.dg/template/dr314.C diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 05363653691..753b3148ab3 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -6266,6 +6266,32 @@ cp_parser_unqualified_id (cp_parser* parser, } } +/* Check [temp.names]/5: A name prefixed by the keyword template shall + be a template-id or the name shall refer to a class template or an + alias template. */ + +static void +check_template_keyword_in_nested_name_spec (tree name) +{ + if (CLASS_TYPE_P (name) + && ((CLASSTYPE_USE_TEMPLATE (name) + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) + || CLASSTYPE_IS_TEMPLATE (name))) + return; + + if (TREE_CODE (name) == TYPENAME_TYPE + && TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) + return; + /* Alias templates are also OK. */ + else if (alias_template_specialization_p (name, nt_opaque)) + return; + + permerror (input_location, TYPE_P (name) + ? G_("%qT is not a template") + : G_("%qD is not a template"), + name); +} + /* Parse an (optional) nested-name-specifier. nested-name-specifier: [C++98] @@ -6389,7 +6415,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, /* Look for the optional `template' keyword, if this isn't the first time through the loop. */ if (success) - template_keyword_p = cp_parser_optional_template_keyword (parser); + { + template_keyword_p = cp_parser_optional_template_keyword (parser); + /* DR1710: "In a qualified-id used as the name in + a typename-specifier, elaborated-type-specifier, using-declaration, + or class-or-decltype, an optional keyword template appearing at + the top level is ignored." */ + if (!template_keyword_p + && typename_keyword_p + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) + template_keyword_p = true; + } /* Save the old scope since the name lookup we are about to do might destroy it. */ @@ -6580,18 +6616,8 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, if (TREE_CODE (new_scope) == TYPE_DECL) new_scope = TREE_TYPE (new_scope); /* Uses of "template" must be followed by actual templates. */ - if (template_keyword_p - && !(CLASS_TYPE_P (new_scope) - && ((CLASSTYPE_USE_TEMPLATE (new_scope) - && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (new_scope))) - || CLASSTYPE_IS_TEMPLATE (new_scope))) - && !(TREE_CODE (new_scope) == TYPENAME_TYPE - && (TREE_CODE (TYPENAME_TYPE_FULLNAME (new_scope)) - == TEMPLATE_ID_EXPR))) - permerror (input_location, TYPE_P (new_scope) - ? G_("%qT is not a template") - : G_("%qD is not a template"), - new_scope); + if (template_keyword_p) + check_template_keyword_in_nested_name_spec (new_scope); /* If it is a class scope, try to complete it; we are about to be looking up names inside the class. */ if (TYPE_P (new_scope) @@ -18120,6 +18146,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, } } } + /* DR 1812: A < following a qualified-id in a typename-specifier + could safely be assumed to begin a template argument list, so + the template keyword should be optional. */ + else if (parser->scope + && qualified_p + && typename_p + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) + { + cp_parser_parse_tentatively (parser); + + type = cp_parser_template_id (parser, + /*template_keyword_p=*/true, + /*check_dependency_p=*/true, + none_type, + /*is_declaration=*/false); + /* This is handled below, so back off. */ + if (type && concept_check_p (type)) + cp_parser_simulate_error (parser); + + if (!cp_parser_parse_definitely (parser)) + type = NULL_TREE; + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) + type = make_typename_type (parser->scope, type, typename_type, + /*complain=*/tf_error); + else if (TREE_CODE (type) != TYPE_DECL) + type = NULL_TREE; + } /* Otherwise, look for a type-name. */ if (!type) diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C new file mode 100644 index 00000000000..e5397e71bd6 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile { target c++14 } } + +template <int> struct S { + template <int> struct A; + template <int N> using U = typename A<N>::foo; +}; +template <typename T> typename S<1>::U<T::foo>::type a; +template <typename T> typename S<1>::template U<T::foo>::type a2; diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C new file mode 100644 index 00000000000..f42b425a30b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C @@ -0,0 +1,8 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile { target c++14 } } + +template <typename T> struct S { + template <typename TT> + using U = TT; +}; +template <typename T> typename S<int>::template U<T>::type foo; diff --git a/gcc/testsuite/g++.dg/parse/missing-template1.C b/gcc/testsuite/g++.dg/parse/missing-template1.C index fcc3aa0c3ff..19c1433d09f 100644 --- a/gcc/testsuite/g++.dg/parse/missing-template1.C +++ b/gcc/testsuite/g++.dg/parse/missing-template1.C @@ -12,9 +12,7 @@ template <typename T> struct A template <typename T> void foo() { - typedef typename A<T>::B<T>::X Y; // { dg-error "non-template" "non" } - // { dg-error "not declare" "decl" { target *-*-* } .-1 } - // { dg-message "note" "note" { target *-*-* } .-2 } + typedef typename A<T>::B<T>::X Y; } void bar() diff --git a/gcc/testsuite/g++.dg/parse/template3.C b/gcc/testsuite/g++.dg/parse/template3.C index c284a5ee040..8da8a48a3c3 100644 --- a/gcc/testsuite/g++.dg/parse/template3.C +++ b/gcc/testsuite/g++.dg/parse/template3.C @@ -13,7 +13,4 @@ struct X : Outer<b>::template Inner<T> {}; template <bool b, typename T> -struct Y : Outer<b>::Inner<T> {}; // { dg-error "used as template" "temp" } -// { dg-error "expected" "exp" { target *-*-* } .-1 } -// { dg-message "note" "note" { target *-*-* } .-2 } - +struct Y : Outer<b>::Inner<T> {}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C new file mode 100644 index 00000000000..18e024f7e6d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C @@ -0,0 +1,18 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> struct B { + typedef int TT; + typedef int TT2; + typedef int TT3; + typedef int TT4; + }; +}; + +struct X : A<int>::B<int> { + using A<int>::template B<int>::TT; + using typename A<int>::template B<int>::TT2; + using A<int>::B<int>::TT3; + using typename A<int>::B<int>::TT4; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C new file mode 100644 index 00000000000..687a9bd5df5 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C @@ -0,0 +1,15 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> + struct W { }; +}; + +void +g () +{ + // class-key nested-name-specifier template[opt] simple-template-id + struct A<int>::W<int> w; + struct A<int>::template W<int> w2; +} diff --git a/gcc/testsuite/g++.dg/template/dependent-name12.C b/gcc/testsuite/g++.dg/template/dependent-name12.C new file mode 100644 index 00000000000..7ee94e7457d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name12.C @@ -0,0 +1,7 @@ +// PR c++/94057 - template keyword in a typename-specifier. + +template <bool> struct A; +template <typename, typename> struct B; +template <typename T, typename U, typename V> struct B<T U::*, V> { + typename A<V::x>::type::type t; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name13.C b/gcc/testsuite/g++.dg/template/dependent-name13.C new file mode 100644 index 00000000000..1e971168657 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name13.C @@ -0,0 +1,8 @@ +// DR 1710 - Missing template keyword in class-or-decltype + +template<typename T> struct S { + void fn(typename T::template B<int>::template C<int>); + void fn2(typename T::B<int>::template C<int>); + void fn3(typename T::template B<int>::C<int>); + void fn4(typename T::B<int>::C<int>); +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C index fc78983324b..15c1acb0347 100644 --- a/gcc/testsuite/g++.dg/template/dependent-name5.C +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C @@ -22,9 +22,7 @@ struct A typedef N<int> type6; typedef A::N<int> type7; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T>::N<int> type8; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } typedef typename A<T*>::template N<int> type10; diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C new file mode 100644 index 00000000000..3dfa42d2df0 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(A<T>::B<U>&); + void fn(A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C new file mode 100644 index 00000000000..ad9e44f9b85 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::B<U>&); + void fn(typename A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C new file mode 100644 index 00000000000..6dfdbc176c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::template B<U>&); + void fn(typename A<T>::template B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C new file mode 100644 index 00000000000..99d49b746b2 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C @@ -0,0 +1,10 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + }; +}; + +template<typename T> struct D : A<int>::B<int> {}; +template<typename T> struct D2 : A<int>::template B<int> {}; diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C new file mode 100644 index 00000000000..c945977971f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct D : T::template B<int>::template C<int> {}; +template<typename T> struct D2 : T::B<int>::template C<int> {}; +template<typename T> struct D3 : T::template B<int>::C<int> {}; +template<typename T> struct D4 : T::B<int>::C<int> {}; +template<typename T> struct D5 : T::template B<int>::type::type {}; +template<typename T> struct D6 : T::B<int>::type::type {}; diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C new file mode 100644 index 00000000000..f629d7d0b98 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1794.C @@ -0,0 +1,14 @@ +// DR 1794 - template keyword and alias templates. +// { dg-do compile { target c++11 } } + +template<template<typename> class Template> +struct Internal { + template<typename Arg> + using Bind = Template<Arg>; +}; + +template<template<typename> class Template, typename Arg> +using Instantiate = Template<Arg>; + +template<template<typename> class Template, typename Argument> +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C new file mode 100644 index 00000000000..7c0d8ac592f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr314.C @@ -0,0 +1,15 @@ +// DR 314 - template in base class specifier. + +template <typename T> +struct A { + template <typename U> + struct B {}; +}; + +template <typename T> +struct C : public A<T>::template B<T> { +}; + +template <typename T> +struct C2 : public A<int>::B<T> { +}; diff --git a/gcc/testsuite/g++.dg/template/error4.C b/gcc/testsuite/g++.dg/template/error4.C index 9d76561aa02..a5030f06c98 100644 --- a/gcc/testsuite/g++.dg/template/error4.C +++ b/gcc/testsuite/g++.dg/template/error4.C @@ -5,5 +5,4 @@ template<class T> struct C1 }; template<class T, class U> -void foo(typename C1<T>::C2<U>::Type *) { } // { dg-error "template" "error " } -// { dg-message "note" "note" { target *-*-* } .-1 } +void foo(typename C1<T>::C2<U>::Type *) { } diff --git a/gcc/testsuite/g++.dg/template/meminit2.C b/gcc/testsuite/g++.dg/template/meminit2.C index db6e0427fc7..6a56a806746 100644 --- a/gcc/testsuite/g++.dg/template/meminit2.C +++ b/gcc/testsuite/g++.dg/template/meminit2.C @@ -14,8 +14,6 @@ struct A : typename O<T>::template I<int> { // { dg-error "keyword 'typename' template <typename T> struct B : O<T>::template I<int> { - B() : O<T>::I<int>() // { dg-error "used as template|it is a template" } + B() : O<T>::I<int>() {} }; - -// { dg-bogus "end of input" "bogus token skipping in the parser" { xfail *-*-* } 17 } diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C index 5d386132436..60cd5e3f44e 100644 --- a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C +++ b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C @@ -3,10 +3,8 @@ template <class T> struct S { - typedef typename T::Y<T>::Z X; // { dg-error "non-template" "non-template" } No Y in A -// { dg-message "note" "note" { target *-*-* } .-1 } -// { dg-error "does not declare" "not declare" { target *-*-* } .-2 } - X x; // { dg-error "does not name a type" } No Y in A + typedef typename T::Y<T>::Z X; // { dg-error "not a class template" } No Y in A + X x; }; struct A { base-commit: 48817fbd7616f086ac7bb1dd38b862f78762c9b8
On 3/25/20 5:36 PM, Marek Polacek wrote: > On Wed, Mar 25, 2020 at 12:00:24AM -0400, Jason Merrill wrote: >> On 3/24/20 11:45 AM, Marek Polacek wrote: >>> On Mon, Mar 23, 2020 at 10:41:28AM -0400, Jason Merrill wrote: >>>> On 3/20/20 7:02 PM, Marek Polacek wrote: >>>>> On Fri, Mar 20, 2020 at 02:12:49PM -0400, Jason Merrill wrote: >>>>>> On 3/20/20 1:06 PM, Marek Polacek wrote: >>>>>>> Wonderful. I've added a bunch of tests, and some from the related DRs too. >>>>>>> But I had a problem with the class-or-decltype case: if we have >>>>>>> >>>>>>> template<typename T> struct D : T::template B<int>::template C<int> {}; >>>>>>> >>>>>>> then we still require all the 'template' keywords here (as does clang). So I'm >>>>>>> kind of confused, but I don't think it's a big deal right now. >>>>>> >>>>>> This seems related enough that I'd like to fix it at the same time; why >>>>>> doesn't your patch fix it? Is it because typename_p is false? >>>>> >>>>> Ah, I was mistaken. Of course we need the template keyword here: it's a member of an >>>>> unknown specialization! >>>> >>>> That's why it's needed in contexts where we don't know whether or not we're >>>> naming a type. But where we do know that, as in a base-specifier, it isn't >>>> necessary. This is exactly DR 1710: "The keyword template is optional in a >>>> ... class-or-decltype (Clause 11.7 [class.derived])...." >>> >>> Duh, not sure what I was thinking. >>> >>> I've implemented that in cp_parser_nested_name_specifier_opt: assume 'template' >>> if we've seen 'typename'. If it turns out that this is wrong because it >>> triggers in contexts where it shouldn't, we'll have to introduce something like >>> CP_PARSER_FLAGS_TEMPLATE_OPTIONAL. >>> >>> With this another problem revealed: we weren't accepting an alias template >>> after 'template' which DR1710 says is valid. Fixed by the TYPE_ALIAS_P hunk >>> in the new check_template_keyword_in_nested_name_spec. (alias-decl1.C) >>> >>> But this is still not over: I noticed that >>> >>> template <typename T> struct S { >>> template <typename TT> >>> using U = TT; >>> }; >>> template <typename T> typename S<int>::template U<T>::type foo; >>> >>> is still rejected and shouldn't be. Here check_template_keyword_in_nested_name_spec >>> gets >>> >>> <template_type_parm 0x7fffeaa42690 U type_0 VOID >>> align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type 0x7fffeaa420a8 >>> index 0 level 1 orig_level 2 >>> chain <type_decl 0x7fffea90bda8 TT>> >>> >>> Any suggestions how to handle this? >> >> It should work to check for an alias whether or not the target is a >> TYPENAME_TYPE. > > Hmm, we don't have a TYPENAME_TYPE here at all, but since that template_type_parm > is typedef_variant_p, it can be handled along with... > >>> +static void >>> +check_template_keyword_in_nested_name_spec (tree name) >>> +{ >>> + if (CLASS_TYPE_P (name) >>> + && ((CLASSTYPE_USE_TEMPLATE (name) >>> + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) >>> + || CLASSTYPE_IS_TEMPLATE (name))) >>> + return; >>> + >>> + >>> + if (TREE_CODE (name) == TYPENAME_TYPE) >>> + { >>> + if (TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) >>> + return; >>> + /* Alias templates are also OK. */ >>> + else if (TYPE_ALIAS_P (name)) >>> + { >>> + tree tinfo = TYPE_ALIAS_TEMPLATE_INFO (name); >>> + if (tinfo && DECL_ALIAS_TEMPLATE_P (TI_TEMPLATE (tinfo))) >>> + return; >>> + } >>> + } >> >> I think you want to check all typedefs like in e.g. find_parameter_packs_r; >> if the name is a typedef, it's only suitable if >> alias_template_specialization_p. > > ..this: Since alias_template_specialization_p already checks TYPE_P and > typedef_variant_p, can we simply use that? But not all typedefs are aliases; 'typedef A<int> type;' does not make '::template type' valid just because '::template A<int>' would be. If it's an alias template specialization, OK; if it's any other typedef, not OK. >>> /* Parse an (optional) nested-name-specifier. >>> nested-name-specifier: [C++98] >>> @@ -6389,7 +6422,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, >>> /* Look for the optional `template' keyword, if this isn't the >>> first time through the loop. */ >>> if (success) >>> - template_keyword_p = cp_parser_optional_template_keyword (parser); >>> + { >>> + template_keyword_p = cp_parser_optional_template_keyword (parser); >>> + /* DR1710: "In a qualified-id used as the name in >>> + a typename-specifier, elaborated-type-specifier, using-declaration, >>> + or class-or-decltype, an optional keyword template appearing at >>> + the top level is ignored." */ >>> + if (!template_keyword_p >>> + && typename_keyword_p >>> + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) >>> + template_keyword_p = true; >>> + } > > And since we now do this, we don't need... > >>> @@ -23636,8 +23696,9 @@ cp_parser_class_name (cp_parser *parser, >>> && decl != error_mark_node >>> && !is_overloaded_fn (decl)) >>> { >>> - decl = make_typename_type (scope, decl, typename_type, >>> - /*complain=*/tf_error); >>> + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) >>> + ? tf_none : tf_error); >>> + decl = make_typename_type (scope, decl, typename_type, complain); >> >> Why? > > ...this hunk, so dropped. New test alias-decl2.C added, otherwise no changes. > > Bootstrapped/regtested on x86_64-linux, ok for trunk? > > -- >8 -- > Consider > > template <typename T> class A { > template <typename U> class B { > void fn(typename A<T>::B<U>); > }; > }; > > which is rejected with > error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type > whereas clang/icc/msvc accept it. > > "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments > don't mention it anywhere, because the typename-specifier wasn't in C++11; > it was only added to the language in N1376. Instead, we handle it as > an elaborated-type-specifier (not a problem thus far). So we get to > cp_parser_nested_name_specifier_opt which has a loop that breaks if we > don't see a < or ::, but that means we can -- tentatively -- parse even > B<U> which is not a nested-name-specifier (it doesn't end with a ::). > > I think this should compile because [temp.names]/4 says: "In a qualified-id > used as the name in a typename-specifier, elaborated-type-specifier, > using-declaration, or class-or-decltype, an optional keyword template > appearing at the top level is ignored.", added in DR 1710. Also see > DR 1812. > > This issue on its own is not a significant problem or a regression. > However, in C++20, the typename here becomes optional, and so this test > is rejected in C++20, but accepted in C++17: > > template <typename T> class A { > template <typename U> class B { > void fn(A<T>::B<U>); > }; > }; > > Here we morph A<T>::B<U> into a typename-specifier, but that happens > in cp_parser_simple_type_specifier and we never handle it as above. > To fake the template keyword I'm afraid we need to use cp_parser_template_id > with template_keyword_p=true as in the patch below. The tricky thing > is to avoid breaking concepts. > > To handle DR 1710, I made cp_parser_nested_name_specifier_opt assume that > when we're naming a type, the template keyword is present, too. That > revealed a bug: DR 1710 also says that the template keyword can be followed > by an alias template, but we weren't prepared to handle that. alias-decl?.C > exercise this. > > DR 1710 > PR c++/94057 - template keyword in a typename-specifier. > * parser.c (check_template_keyword_in_nested_name_spec): New. > (cp_parser_nested_name_specifier_opt): Implement DR1710, optional > 'template'. Call check_template_keyword_in_nested_name_spec. > (cp_parser_simple_type_specifier): Assume that a < > following a qualified-id in a typename-specifier begins > a template argument list. > > * g++.dg/cpp1y/alias-decl1.C: New test. > * g++.dg/cpp1y/alias-decl2.C: New test. > * g++.dg/parse/missing-template1.C: Update dg-error. > * g++.dg/parse/template3.C: Likewise. > * g++.dg/template/error4.C: Likewise. > * g++.dg/template/meminit2.C: Likewise. > * g++.dg/template/dependent-name5.C: Likewise. > * g++.dg/template/dependent-name7.C: New test. > * g++.dg/template/dependent-name8.C: New test. > * g++.dg/template/dependent-name9.C: New test. > * g++.dg/template/dependent-name10.C: New test. > * g++.dg/template/dependent-name11.C: New test. > * g++.dg/template/dependent-name12.C: New test. > * g++.dg/template/dependent-name13.C: New test. > * g++.dg/template/dr1794.C: New test. > * g++.dg/template/dr314.C: New test. > * g++.dg/template/dr1710.C: New test. > * g++.dg/template/dr1710-2.C: New test. > * g++.old-deja/g++.pt/crash38.C: Update dg-error. > --- > gcc/cp/parser.c | 79 ++++++++++++++++--- > gcc/testsuite/g++.dg/cpp1y/alias-decl1.C | 9 +++ > gcc/testsuite/g++.dg/cpp1y/alias-decl2.C | 8 ++ > .../g++.dg/parse/missing-template1.C | 4 +- > gcc/testsuite/g++.dg/parse/template3.C | 5 +- > .../g++.dg/template/dependent-name10.C | 18 +++++ > .../g++.dg/template/dependent-name11.C | 15 ++++ > .../g++.dg/template/dependent-name12.C | 7 ++ > .../g++.dg/template/dependent-name13.C | 8 ++ > .../g++.dg/template/dependent-name5.C | 2 - > .../g++.dg/template/dependent-name7.C | 9 +++ > .../g++.dg/template/dependent-name8.C | 9 +++ > .../g++.dg/template/dependent-name9.C | 9 +++ > gcc/testsuite/g++.dg/template/dr1710-2.C | 10 +++ > gcc/testsuite/g++.dg/template/dr1710.C | 9 +++ > gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++ > gcc/testsuite/g++.dg/template/dr314.C | 15 ++++ > gcc/testsuite/g++.dg/template/error4.C | 3 +- > gcc/testsuite/g++.dg/template/meminit2.C | 4 +- > gcc/testsuite/g++.old-deja/g++.pt/crash38.C | 6 +- > 20 files changed, 212 insertions(+), 31 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl2.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name12.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name13.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C > create mode 100644 gcc/testsuite/g++.dg/template/dr314.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index 05363653691..753b3148ab3 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -6266,6 +6266,32 @@ cp_parser_unqualified_id (cp_parser* parser, > } > } > > +/* Check [temp.names]/5: A name prefixed by the keyword template shall > + be a template-id or the name shall refer to a class template or an > + alias template. */ > + > +static void > +check_template_keyword_in_nested_name_spec (tree name) > +{ > + if (CLASS_TYPE_P (name) > + && ((CLASSTYPE_USE_TEMPLATE (name) > + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) > + || CLASSTYPE_IS_TEMPLATE (name))) > + return; > + > + if (TREE_CODE (name) == TYPENAME_TYPE > + && TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) > + return; > + /* Alias templates are also OK. */ > + else if (alias_template_specialization_p (name, nt_opaque)) > + return; > + > + permerror (input_location, TYPE_P (name) > + ? G_("%qT is not a template") > + : G_("%qD is not a template"), > + name); > +} > + > /* Parse an (optional) nested-name-specifier. > > nested-name-specifier: [C++98] > @@ -6389,7 +6415,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > /* Look for the optional `template' keyword, if this isn't the > first time through the loop. */ > if (success) > - template_keyword_p = cp_parser_optional_template_keyword (parser); > + { > + template_keyword_p = cp_parser_optional_template_keyword (parser); > + /* DR1710: "In a qualified-id used as the name in > + a typename-specifier, elaborated-type-specifier, using-declaration, > + or class-or-decltype, an optional keyword template appearing at > + the top level is ignored." */ > + if (!template_keyword_p > + && typename_keyword_p > + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) > + template_keyword_p = true; > + } > > /* Save the old scope since the name lookup we are about to do > might destroy it. */ > @@ -6580,18 +6616,8 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > if (TREE_CODE (new_scope) == TYPE_DECL) > new_scope = TREE_TYPE (new_scope); > /* Uses of "template" must be followed by actual templates. */ > - if (template_keyword_p > - && !(CLASS_TYPE_P (new_scope) > - && ((CLASSTYPE_USE_TEMPLATE (new_scope) > - && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (new_scope))) > - || CLASSTYPE_IS_TEMPLATE (new_scope))) > - && !(TREE_CODE (new_scope) == TYPENAME_TYPE > - && (TREE_CODE (TYPENAME_TYPE_FULLNAME (new_scope)) > - == TEMPLATE_ID_EXPR))) > - permerror (input_location, TYPE_P (new_scope) > - ? G_("%qT is not a template") > - : G_("%qD is not a template"), > - new_scope); > + if (template_keyword_p) > + check_template_keyword_in_nested_name_spec (new_scope); > /* If it is a class scope, try to complete it; we are about to > be looking up names inside the class. */ > if (TYPE_P (new_scope) > @@ -18120,6 +18146,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, > } > } > } > + /* DR 1812: A < following a qualified-id in a typename-specifier > + could safely be assumed to begin a template argument list, so > + the template keyword should be optional. */ > + else if (parser->scope > + && qualified_p > + && typename_p > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) > + { > + cp_parser_parse_tentatively (parser); > + > + type = cp_parser_template_id (parser, > + /*template_keyword_p=*/true, > + /*check_dependency_p=*/true, > + none_type, > + /*is_declaration=*/false); > + /* This is handled below, so back off. */ > + if (type && concept_check_p (type)) > + cp_parser_simulate_error (parser); > + > + if (!cp_parser_parse_definitely (parser)) > + type = NULL_TREE; > + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) > + type = make_typename_type (parser->scope, type, typename_type, > + /*complain=*/tf_error); > + else if (TREE_CODE (type) != TYPE_DECL) > + type = NULL_TREE; > + } > > /* Otherwise, look for a type-name. */ > if (!type) > diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > new file mode 100644 > index 00000000000..e5397e71bd6 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile { target c++14 } } > + > +template <int> struct S { > + template <int> struct A; > + template <int N> using U = typename A<N>::foo; > +}; > +template <typename T> typename S<1>::U<T::foo>::type a; > +template <typename T> typename S<1>::template U<T::foo>::type a2; > diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C > new file mode 100644 > index 00000000000..f42b425a30b > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C > @@ -0,0 +1,8 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile { target c++14 } } > + > +template <typename T> struct S { > + template <typename TT> > + using U = TT; > +}; > +template <typename T> typename S<int>::template U<T>::type foo; > diff --git a/gcc/testsuite/g++.dg/parse/missing-template1.C b/gcc/testsuite/g++.dg/parse/missing-template1.C > index fcc3aa0c3ff..19c1433d09f 100644 > --- a/gcc/testsuite/g++.dg/parse/missing-template1.C > +++ b/gcc/testsuite/g++.dg/parse/missing-template1.C > @@ -12,9 +12,7 @@ template <typename T> struct A > > template <typename T> void foo() > { > - typedef typename A<T>::B<T>::X Y; // { dg-error "non-template" "non" } > - // { dg-error "not declare" "decl" { target *-*-* } .-1 } > - // { dg-message "note" "note" { target *-*-* } .-2 } > + typedef typename A<T>::B<T>::X Y; > } > > void bar() > diff --git a/gcc/testsuite/g++.dg/parse/template3.C b/gcc/testsuite/g++.dg/parse/template3.C > index c284a5ee040..8da8a48a3c3 100644 > --- a/gcc/testsuite/g++.dg/parse/template3.C > +++ b/gcc/testsuite/g++.dg/parse/template3.C > @@ -13,7 +13,4 @@ struct X : Outer<b>::template Inner<T> > {}; > > template <bool b, typename T> > -struct Y : Outer<b>::Inner<T> {}; // { dg-error "used as template" "temp" } > -// { dg-error "expected" "exp" { target *-*-* } .-1 } > -// { dg-message "note" "note" { target *-*-* } .-2 } > - > +struct Y : Outer<b>::Inner<T> {}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C > new file mode 100644 > index 00000000000..18e024f7e6d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C > @@ -0,0 +1,18 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> struct B { > + typedef int TT; > + typedef int TT2; > + typedef int TT3; > + typedef int TT4; > + }; > +}; > + > +struct X : A<int>::B<int> { > + using A<int>::template B<int>::TT; > + using typename A<int>::template B<int>::TT2; > + using A<int>::B<int>::TT3; > + using typename A<int>::B<int>::TT4; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C > new file mode 100644 > index 00000000000..687a9bd5df5 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C > @@ -0,0 +1,15 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> > + struct W { }; > +}; > + > +void > +g () > +{ > + // class-key nested-name-specifier template[opt] simple-template-id > + struct A<int>::W<int> w; > + struct A<int>::template W<int> w2; > +} > diff --git a/gcc/testsuite/g++.dg/template/dependent-name12.C b/gcc/testsuite/g++.dg/template/dependent-name12.C > new file mode 100644 > index 00000000000..7ee94e7457d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name12.C > @@ -0,0 +1,7 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > + > +template <bool> struct A; > +template <typename, typename> struct B; > +template <typename T, typename U, typename V> struct B<T U::*, V> { > + typename A<V::x>::type::type t; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name13.C b/gcc/testsuite/g++.dg/template/dependent-name13.C > new file mode 100644 > index 00000000000..1e971168657 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name13.C > @@ -0,0 +1,8 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > + > +template<typename T> struct S { > + void fn(typename T::template B<int>::template C<int>); > + void fn2(typename T::B<int>::template C<int>); > + void fn3(typename T::template B<int>::C<int>); > + void fn4(typename T::B<int>::C<int>); > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C > index fc78983324b..15c1acb0347 100644 > --- a/gcc/testsuite/g++.dg/template/dependent-name5.C > +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C > @@ -22,9 +22,7 @@ struct A > > typedef N<int> type6; > typedef A::N<int> type7; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T>::N<int> type8; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } > typedef typename A<T*>::template N<int> type10; > > diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C > new file mode 100644 > index 00000000000..3dfa42d2df0 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(A<T>::B<U>&); > + void fn(A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C > new file mode 100644 > index 00000000000..ad9e44f9b85 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::B<U>&); > + void fn(typename A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C > new file mode 100644 > index 00000000000..6dfdbc176c1 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::template B<U>&); > + void fn(typename A<T>::template B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C > new file mode 100644 > index 00000000000..99d49b746b2 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C > @@ -0,0 +1,10 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + }; > +}; > + > +template<typename T> struct D : A<int>::B<int> {}; > +template<typename T> struct D2 : A<int>::template B<int> {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C > new file mode 100644 > index 00000000000..c945977971f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct D : T::template B<int>::template C<int> {}; > +template<typename T> struct D2 : T::B<int>::template C<int> {}; > +template<typename T> struct D3 : T::template B<int>::C<int> {}; > +template<typename T> struct D4 : T::B<int>::C<int> {}; > +template<typename T> struct D5 : T::template B<int>::type::type {}; > +template<typename T> struct D6 : T::B<int>::type::type {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C > new file mode 100644 > index 00000000000..f629d7d0b98 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1794.C > @@ -0,0 +1,14 @@ > +// DR 1794 - template keyword and alias templates. > +// { dg-do compile { target c++11 } } > + > +template<template<typename> class Template> > +struct Internal { > + template<typename Arg> > + using Bind = Template<Arg>; > +}; > + > +template<template<typename> class Template, typename Arg> > +using Instantiate = Template<Arg>; > + > +template<template<typename> class Template, typename Argument> > +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; > diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C > new file mode 100644 > index 00000000000..7c0d8ac592f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr314.C > @@ -0,0 +1,15 @@ > +// DR 314 - template in base class specifier. > + > +template <typename T> > +struct A { > + template <typename U> > + struct B {}; > +}; > + > +template <typename T> > +struct C : public A<T>::template B<T> { > +}; > + > +template <typename T> > +struct C2 : public A<int>::B<T> { > +}; > diff --git a/gcc/testsuite/g++.dg/template/error4.C b/gcc/testsuite/g++.dg/template/error4.C > index 9d76561aa02..a5030f06c98 100644 > --- a/gcc/testsuite/g++.dg/template/error4.C > +++ b/gcc/testsuite/g++.dg/template/error4.C > @@ -5,5 +5,4 @@ template<class T> struct C1 > }; > > template<class T, class U> > -void foo(typename C1<T>::C2<U>::Type *) { } // { dg-error "template" "error " } > -// { dg-message "note" "note" { target *-*-* } .-1 } > +void foo(typename C1<T>::C2<U>::Type *) { } > diff --git a/gcc/testsuite/g++.dg/template/meminit2.C b/gcc/testsuite/g++.dg/template/meminit2.C > index db6e0427fc7..6a56a806746 100644 > --- a/gcc/testsuite/g++.dg/template/meminit2.C > +++ b/gcc/testsuite/g++.dg/template/meminit2.C > @@ -14,8 +14,6 @@ struct A : typename O<T>::template I<int> { // { dg-error "keyword 'typename' > > template <typename T> > struct B : O<T>::template I<int> { > - B() : O<T>::I<int>() // { dg-error "used as template|it is a template" } > + B() : O<T>::I<int>() > {} > }; > - > -// { dg-bogus "end of input" "bogus token skipping in the parser" { xfail *-*-* } 17 } > diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > index 5d386132436..60cd5e3f44e 100644 > --- a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > +++ b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > @@ -3,10 +3,8 @@ > > template <class T> > struct S { > - typedef typename T::Y<T>::Z X; // { dg-error "non-template" "non-template" } No Y in A > -// { dg-message "note" "note" { target *-*-* } .-1 } > -// { dg-error "does not declare" "not declare" { target *-*-* } .-2 } > - X x; // { dg-error "does not name a type" } No Y in A > + typedef typename T::Y<T>::Z X; // { dg-error "not a class template" } No Y in A > + X x; > }; > > struct A { > > base-commit: 48817fbd7616f086ac7bb1dd38b862f78762c9b8 >
On Thu, Mar 26, 2020 at 01:43:28AM -0400, Jason Merrill wrote: > > > I think you want to check all typedefs like in e.g. find_parameter_packs_r; > > > if the name is a typedef, it's only suitable if > > > alias_template_specialization_p. > > > > ..this: Since alias_template_specialization_p already checks TYPE_P and > > typedef_variant_p, can we simply use that? > > But not all typedefs are aliases; 'typedef A<int> type;' does not make > '::template type' valid just because '::template A<int>' would be. If it's > an alias template specialization, OK; if it's any other typedef, not OK. This is actually already handled well, '::template type' is rejected but '::template A<int>' works. I've added alias-decl3.C to that effect but otherwise there are no changes in this patch: -- >8 -- Consider template <typename T> class A { template <typename U> class B { void fn(typename A<T>::B<U>); }; }; which is rejected with error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type whereas clang/icc/msvc accept it. "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments don't mention it anywhere, because the typename-specifier wasn't in C++11; it was only added to the language in N1376. Instead, we handle it as an elaborated-type-specifier (not a problem thus far). So we get to cp_parser_nested_name_specifier_opt which has a loop that breaks if we don't see a < or ::, but that means we can -- tentatively -- parse even B<U> which is not a nested-name-specifier (it doesn't end with a ::). I think this should compile because [temp.names]/4 says: "In a qualified-id used as the name in a typename-specifier, elaborated-type-specifier, using-declaration, or class-or-decltype, an optional keyword template appearing at the top level is ignored.", added in DR 1710. Also see DR 1812. This issue on its own is not a significant problem or a regression. However, in C++20, the typename here becomes optional, and so this test is rejected in C++20, but accepted in C++17: template <typename T> class A { template <typename U> class B { void fn(A<T>::B<U>); }; }; Here we morph A<T>::B<U> into a typename-specifier, but that happens in cp_parser_simple_type_specifier and we never handle it as above. To fake the template keyword I'm afraid we need to use cp_parser_template_id with template_keyword_p=true as in the patch below. The tricky thing is to avoid breaking concepts. To handle DR 1710, I made cp_parser_nested_name_specifier_opt assume that when we're naming a type, the template keyword is present, too. That revealed a bug: DR 1710 also says that the template keyword can be followed by an alias template, but we weren't prepared to handle that. alias-decl?.C exercise this. gcc/cp: DR 1710 PR c++/94057 - template keyword in a typename-specifier. * parser.c (check_template_keyword_in_nested_name_spec): New. (cp_parser_nested_name_specifier_opt): Implement DR1710, optional 'template'. Call check_template_keyword_in_nested_name_spec. (cp_parser_simple_type_specifier): Assume that a < following a qualified-id in a typename-specifier begins a template argument list. gcc/testsuite: DR 1710 PR c++/94057 - template keyword in a typename-specifier. * g++.dg/cpp1y/alias-decl1.C: New test. * g++.dg/cpp1y/alias-decl2.C: New test. * g++.dg/cpp1y/alias-decl3.C: New test. * g++.dg/parse/missing-template1.C: Update dg-error. * g++.dg/parse/template3.C: Likewise. * g++.dg/template/error4.C: Likewise. * g++.dg/template/meminit2.C: Likewise. * g++.dg/template/dependent-name5.C: Likewise. * g++.dg/template/dependent-name7.C: New test. * g++.dg/template/dependent-name8.C: New test. * g++.dg/template/dependent-name9.C: New test. * g++.dg/template/dependent-name10.C: New test. * g++.dg/template/dependent-name11.C: New test. * g++.dg/template/dependent-name12.C: New test. * g++.dg/template/dependent-name13.C: New test. * g++.dg/template/dr1794.C: New test. * g++.dg/template/dr314.C: New test. * g++.dg/template/dr1710.C: New test. * g++.dg/template/dr1710-2.C: New test. * g++.old-deja/g++.pt/crash38.C: Update dg-error. --- gcc/cp/parser.c | 79 ++++++++++++++++--- gcc/testsuite/g++.dg/cpp1y/alias-decl1.C | 9 +++ gcc/testsuite/g++.dg/cpp1y/alias-decl2.C | 8 ++ gcc/testsuite/g++.dg/cpp1y/alias-decl3.C | 9 +++ .../g++.dg/parse/missing-template1.C | 4 +- gcc/testsuite/g++.dg/parse/template3.C | 5 +- .../g++.dg/template/dependent-name10.C | 18 +++++ .../g++.dg/template/dependent-name11.C | 15 ++++ .../g++.dg/template/dependent-name12.C | 7 ++ .../g++.dg/template/dependent-name13.C | 8 ++ .../g++.dg/template/dependent-name5.C | 2 - .../g++.dg/template/dependent-name7.C | 9 +++ .../g++.dg/template/dependent-name8.C | 9 +++ .../g++.dg/template/dependent-name9.C | 9 +++ gcc/testsuite/g++.dg/template/dr1710-2.C | 10 +++ gcc/testsuite/g++.dg/template/dr1710.C | 9 +++ gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++ gcc/testsuite/g++.dg/template/dr314.C | 15 ++++ gcc/testsuite/g++.dg/template/error4.C | 3 +- gcc/testsuite/g++.dg/template/meminit2.C | 4 +- gcc/testsuite/g++.old-deja/g++.pt/crash38.C | 6 +- 21 files changed, 221 insertions(+), 31 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl1.C create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl2.C create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl3.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name12.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name13.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C create mode 100644 gcc/testsuite/g++.dg/template/dr314.C diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 05363653691..753b3148ab3 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -6266,6 +6266,32 @@ cp_parser_unqualified_id (cp_parser* parser, } } +/* Check [temp.names]/5: A name prefixed by the keyword template shall + be a template-id or the name shall refer to a class template or an + alias template. */ + +static void +check_template_keyword_in_nested_name_spec (tree name) +{ + if (CLASS_TYPE_P (name) + && ((CLASSTYPE_USE_TEMPLATE (name) + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) + || CLASSTYPE_IS_TEMPLATE (name))) + return; + + if (TREE_CODE (name) == TYPENAME_TYPE + && TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) + return; + /* Alias templates are also OK. */ + else if (alias_template_specialization_p (name, nt_opaque)) + return; + + permerror (input_location, TYPE_P (name) + ? G_("%qT is not a template") + : G_("%qD is not a template"), + name); +} + /* Parse an (optional) nested-name-specifier. nested-name-specifier: [C++98] @@ -6389,7 +6415,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, /* Look for the optional `template' keyword, if this isn't the first time through the loop. */ if (success) - template_keyword_p = cp_parser_optional_template_keyword (parser); + { + template_keyword_p = cp_parser_optional_template_keyword (parser); + /* DR1710: "In a qualified-id used as the name in + a typename-specifier, elaborated-type-specifier, using-declaration, + or class-or-decltype, an optional keyword template appearing at + the top level is ignored." */ + if (!template_keyword_p + && typename_keyword_p + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) + template_keyword_p = true; + } /* Save the old scope since the name lookup we are about to do might destroy it. */ @@ -6580,18 +6616,8 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, if (TREE_CODE (new_scope) == TYPE_DECL) new_scope = TREE_TYPE (new_scope); /* Uses of "template" must be followed by actual templates. */ - if (template_keyword_p - && !(CLASS_TYPE_P (new_scope) - && ((CLASSTYPE_USE_TEMPLATE (new_scope) - && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (new_scope))) - || CLASSTYPE_IS_TEMPLATE (new_scope))) - && !(TREE_CODE (new_scope) == TYPENAME_TYPE - && (TREE_CODE (TYPENAME_TYPE_FULLNAME (new_scope)) - == TEMPLATE_ID_EXPR))) - permerror (input_location, TYPE_P (new_scope) - ? G_("%qT is not a template") - : G_("%qD is not a template"), - new_scope); + if (template_keyword_p) + check_template_keyword_in_nested_name_spec (new_scope); /* If it is a class scope, try to complete it; we are about to be looking up names inside the class. */ if (TYPE_P (new_scope) @@ -18120,6 +18146,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, } } } + /* DR 1812: A < following a qualified-id in a typename-specifier + could safely be assumed to begin a template argument list, so + the template keyword should be optional. */ + else if (parser->scope + && qualified_p + && typename_p + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) + { + cp_parser_parse_tentatively (parser); + + type = cp_parser_template_id (parser, + /*template_keyword_p=*/true, + /*check_dependency_p=*/true, + none_type, + /*is_declaration=*/false); + /* This is handled below, so back off. */ + if (type && concept_check_p (type)) + cp_parser_simulate_error (parser); + + if (!cp_parser_parse_definitely (parser)) + type = NULL_TREE; + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) + type = make_typename_type (parser->scope, type, typename_type, + /*complain=*/tf_error); + else if (TREE_CODE (type) != TYPE_DECL) + type = NULL_TREE; + } /* Otherwise, look for a type-name. */ if (!type) diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C new file mode 100644 index 00000000000..e5397e71bd6 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile { target c++14 } } + +template <int> struct S { + template <int> struct A; + template <int N> using U = typename A<N>::foo; +}; +template <typename T> typename S<1>::U<T::foo>::type a; +template <typename T> typename S<1>::template U<T::foo>::type a2; diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C new file mode 100644 index 00000000000..f42b425a30b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C @@ -0,0 +1,8 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile { target c++14 } } + +template <typename T> struct S { + template <typename TT> + using U = TT; +}; +template <typename T> typename S<int>::template U<T>::type foo; diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl3.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl3.C new file mode 100644 index 00000000000..b950b20b5d8 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl3.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile { target c++14 } } + +template <typename T> struct S { + template<typename TT> struct A { }; + typedef A<int> type; +}; +template <typename T> typename S<int>::template A<int> foo; +template <typename T> typename S<int>::template type foo2; // { dg-error "expected template-id" } diff --git a/gcc/testsuite/g++.dg/parse/missing-template1.C b/gcc/testsuite/g++.dg/parse/missing-template1.C index fcc3aa0c3ff..19c1433d09f 100644 --- a/gcc/testsuite/g++.dg/parse/missing-template1.C +++ b/gcc/testsuite/g++.dg/parse/missing-template1.C @@ -12,9 +12,7 @@ template <typename T> struct A template <typename T> void foo() { - typedef typename A<T>::B<T>::X Y; // { dg-error "non-template" "non" } - // { dg-error "not declare" "decl" { target *-*-* } .-1 } - // { dg-message "note" "note" { target *-*-* } .-2 } + typedef typename A<T>::B<T>::X Y; } void bar() diff --git a/gcc/testsuite/g++.dg/parse/template3.C b/gcc/testsuite/g++.dg/parse/template3.C index c284a5ee040..8da8a48a3c3 100644 --- a/gcc/testsuite/g++.dg/parse/template3.C +++ b/gcc/testsuite/g++.dg/parse/template3.C @@ -13,7 +13,4 @@ struct X : Outer<b>::template Inner<T> {}; template <bool b, typename T> -struct Y : Outer<b>::Inner<T> {}; // { dg-error "used as template" "temp" } -// { dg-error "expected" "exp" { target *-*-* } .-1 } -// { dg-message "note" "note" { target *-*-* } .-2 } - +struct Y : Outer<b>::Inner<T> {}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C new file mode 100644 index 00000000000..18e024f7e6d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C @@ -0,0 +1,18 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> struct B { + typedef int TT; + typedef int TT2; + typedef int TT3; + typedef int TT4; + }; +}; + +struct X : A<int>::B<int> { + using A<int>::template B<int>::TT; + using typename A<int>::template B<int>::TT2; + using A<int>::B<int>::TT3; + using typename A<int>::B<int>::TT4; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C new file mode 100644 index 00000000000..687a9bd5df5 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C @@ -0,0 +1,15 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile { target c++11 } } + +template<typename T> struct A { + template<typename U> + struct W { }; +}; + +void +g () +{ + // class-key nested-name-specifier template[opt] simple-template-id + struct A<int>::W<int> w; + struct A<int>::template W<int> w2; +} diff --git a/gcc/testsuite/g++.dg/template/dependent-name12.C b/gcc/testsuite/g++.dg/template/dependent-name12.C new file mode 100644 index 00000000000..7ee94e7457d --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name12.C @@ -0,0 +1,7 @@ +// PR c++/94057 - template keyword in a typename-specifier. + +template <bool> struct A; +template <typename, typename> struct B; +template <typename T, typename U, typename V> struct B<T U::*, V> { + typename A<V::x>::type::type t; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name13.C b/gcc/testsuite/g++.dg/template/dependent-name13.C new file mode 100644 index 00000000000..1e971168657 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name13.C @@ -0,0 +1,8 @@ +// DR 1710 - Missing template keyword in class-or-decltype + +template<typename T> struct S { + void fn(typename T::template B<int>::template C<int>); + void fn2(typename T::B<int>::template C<int>); + void fn3(typename T::template B<int>::C<int>); + void fn4(typename T::B<int>::C<int>); +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C index fc78983324b..15c1acb0347 100644 --- a/gcc/testsuite/g++.dg/template/dependent-name5.C +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C @@ -22,9 +22,7 @@ struct A typedef N<int> type6; typedef A::N<int> type7; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T>::N<int> type8; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } typedef typename A<T*>::template N<int> type10; diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C new file mode 100644 index 00000000000..3dfa42d2df0 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(A<T>::B<U>&); + void fn(A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C new file mode 100644 index 00000000000..ad9e44f9b85 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::B<U>&); + void fn(typename A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C new file mode 100644 index 00000000000..6dfdbc176c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::template B<U>&); + void fn(typename A<T>::template B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C new file mode 100644 index 00000000000..99d49b746b2 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C @@ -0,0 +1,10 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + }; +}; + +template<typename T> struct D : A<int>::B<int> {}; +template<typename T> struct D2 : A<int>::template B<int> {}; diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C new file mode 100644 index 00000000000..c945977971f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1710.C @@ -0,0 +1,9 @@ +// DR 1710 - Missing template keyword in class-or-decltype +// { dg-do compile } + +template<typename T> struct D : T::template B<int>::template C<int> {}; +template<typename T> struct D2 : T::B<int>::template C<int> {}; +template<typename T> struct D3 : T::template B<int>::C<int> {}; +template<typename T> struct D4 : T::B<int>::C<int> {}; +template<typename T> struct D5 : T::template B<int>::type::type {}; +template<typename T> struct D6 : T::B<int>::type::type {}; diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C new file mode 100644 index 00000000000..f629d7d0b98 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr1794.C @@ -0,0 +1,14 @@ +// DR 1794 - template keyword and alias templates. +// { dg-do compile { target c++11 } } + +template<template<typename> class Template> +struct Internal { + template<typename Arg> + using Bind = Template<Arg>; +}; + +template<template<typename> class Template, typename Arg> +using Instantiate = Template<Arg>; + +template<template<typename> class Template, typename Argument> +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C new file mode 100644 index 00000000000..7c0d8ac592f --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dr314.C @@ -0,0 +1,15 @@ +// DR 314 - template in base class specifier. + +template <typename T> +struct A { + template <typename U> + struct B {}; +}; + +template <typename T> +struct C : public A<T>::template B<T> { +}; + +template <typename T> +struct C2 : public A<int>::B<T> { +}; diff --git a/gcc/testsuite/g++.dg/template/error4.C b/gcc/testsuite/g++.dg/template/error4.C index 9d76561aa02..a5030f06c98 100644 --- a/gcc/testsuite/g++.dg/template/error4.C +++ b/gcc/testsuite/g++.dg/template/error4.C @@ -5,5 +5,4 @@ template<class T> struct C1 }; template<class T, class U> -void foo(typename C1<T>::C2<U>::Type *) { } // { dg-error "template" "error " } -// { dg-message "note" "note" { target *-*-* } .-1 } +void foo(typename C1<T>::C2<U>::Type *) { } diff --git a/gcc/testsuite/g++.dg/template/meminit2.C b/gcc/testsuite/g++.dg/template/meminit2.C index db6e0427fc7..6a56a806746 100644 --- a/gcc/testsuite/g++.dg/template/meminit2.C +++ b/gcc/testsuite/g++.dg/template/meminit2.C @@ -14,8 +14,6 @@ struct A : typename O<T>::template I<int> { // { dg-error "keyword 'typename' template <typename T> struct B : O<T>::template I<int> { - B() : O<T>::I<int>() // { dg-error "used as template|it is a template" } + B() : O<T>::I<int>() {} }; - -// { dg-bogus "end of input" "bogus token skipping in the parser" { xfail *-*-* } 17 } diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C index 5d386132436..60cd5e3f44e 100644 --- a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C +++ b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C @@ -3,10 +3,8 @@ template <class T> struct S { - typedef typename T::Y<T>::Z X; // { dg-error "non-template" "non-template" } No Y in A -// { dg-message "note" "note" { target *-*-* } .-1 } -// { dg-error "does not declare" "not declare" { target *-*-* } .-2 } - X x; // { dg-error "does not name a type" } No Y in A + typedef typename T::Y<T>::Z X; // { dg-error "not a class template" } No Y in A + X x; }; struct A { base-commit: 16948c54b7576fb4b27c59915eac71a0c6bf94f6
On 3/26/20 3:44 PM, Marek Polacek wrote: > On Thu, Mar 26, 2020 at 01:43:28AM -0400, Jason Merrill wrote: >>>> I think you want to check all typedefs like in e.g. find_parameter_packs_r; >>>> if the name is a typedef, it's only suitable if >>>> alias_template_specialization_p. >>> >>> ..this: Since alias_template_specialization_p already checks TYPE_P and >>> typedef_variant_p, can we simply use that? >> >> But not all typedefs are aliases; 'typedef A<int> type;' does not make >> '::template type' valid just because '::template A<int>' would be. If it's >> an alias template specialization, OK; if it's any other typedef, not OK. > > This is actually already handled well, '::template type' is rejected but > '::template A<int>' works. I've added alias-decl3.C to that effect but > otherwise there are no changes in this patch: Then the patch is OK, thanks. > -- >8 -- > Consider > > template <typename T> class A { > template <typename U> class B { > void fn(typename A<T>::B<U>); > }; > }; > > which is rejected with > error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type > whereas clang/icc/msvc accept it. > > "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments > don't mention it anywhere, because the typename-specifier wasn't in C++11; > it was only added to the language in N1376. Instead, we handle it as > an elaborated-type-specifier (not a problem thus far). So we get to > cp_parser_nested_name_specifier_opt which has a loop that breaks if we > don't see a < or ::, but that means we can -- tentatively -- parse even > B<U> which is not a nested-name-specifier (it doesn't end with a ::). > > I think this should compile because [temp.names]/4 says: "In a qualified-id > used as the name in a typename-specifier, elaborated-type-specifier, > using-declaration, or class-or-decltype, an optional keyword template > appearing at the top level is ignored.", added in DR 1710. Also see > DR 1812. > > This issue on its own is not a significant problem or a regression. > However, in C++20, the typename here becomes optional, and so this test > is rejected in C++20, but accepted in C++17: > > template <typename T> class A { > template <typename U> class B { > void fn(A<T>::B<U>); > }; > }; > > Here we morph A<T>::B<U> into a typename-specifier, but that happens > in cp_parser_simple_type_specifier and we never handle it as above. > To fake the template keyword I'm afraid we need to use cp_parser_template_id > with template_keyword_p=true as in the patch below. The tricky thing > is to avoid breaking concepts. > > To handle DR 1710, I made cp_parser_nested_name_specifier_opt assume that > when we're naming a type, the template keyword is present, too. That > revealed a bug: DR 1710 also says that the template keyword can be followed > by an alias template, but we weren't prepared to handle that. alias-decl?.C > exercise this. > > gcc/cp: > > DR 1710 > PR c++/94057 - template keyword in a typename-specifier. > * parser.c (check_template_keyword_in_nested_name_spec): New. > (cp_parser_nested_name_specifier_opt): Implement DR1710, optional > 'template'. Call check_template_keyword_in_nested_name_spec. > (cp_parser_simple_type_specifier): Assume that a < > following a qualified-id in a typename-specifier begins > a template argument list. > > gcc/testsuite: > > DR 1710 > PR c++/94057 - template keyword in a typename-specifier. > * g++.dg/cpp1y/alias-decl1.C: New test. > * g++.dg/cpp1y/alias-decl2.C: New test. > * g++.dg/cpp1y/alias-decl3.C: New test. > * g++.dg/parse/missing-template1.C: Update dg-error. > * g++.dg/parse/template3.C: Likewise. > * g++.dg/template/error4.C: Likewise. > * g++.dg/template/meminit2.C: Likewise. > * g++.dg/template/dependent-name5.C: Likewise. > * g++.dg/template/dependent-name7.C: New test. > * g++.dg/template/dependent-name8.C: New test. > * g++.dg/template/dependent-name9.C: New test. > * g++.dg/template/dependent-name10.C: New test. > * g++.dg/template/dependent-name11.C: New test. > * g++.dg/template/dependent-name12.C: New test. > * g++.dg/template/dependent-name13.C: New test. > * g++.dg/template/dr1794.C: New test. > * g++.dg/template/dr314.C: New test. > * g++.dg/template/dr1710.C: New test. > * g++.dg/template/dr1710-2.C: New test. > * g++.old-deja/g++.pt/crash38.C: Update dg-error. > --- > gcc/cp/parser.c | 79 ++++++++++++++++--- > gcc/testsuite/g++.dg/cpp1y/alias-decl1.C | 9 +++ > gcc/testsuite/g++.dg/cpp1y/alias-decl2.C | 8 ++ > gcc/testsuite/g++.dg/cpp1y/alias-decl3.C | 9 +++ > .../g++.dg/parse/missing-template1.C | 4 +- > gcc/testsuite/g++.dg/parse/template3.C | 5 +- > .../g++.dg/template/dependent-name10.C | 18 +++++ > .../g++.dg/template/dependent-name11.C | 15 ++++ > .../g++.dg/template/dependent-name12.C | 7 ++ > .../g++.dg/template/dependent-name13.C | 8 ++ > .../g++.dg/template/dependent-name5.C | 2 - > .../g++.dg/template/dependent-name7.C | 9 +++ > .../g++.dg/template/dependent-name8.C | 9 +++ > .../g++.dg/template/dependent-name9.C | 9 +++ > gcc/testsuite/g++.dg/template/dr1710-2.C | 10 +++ > gcc/testsuite/g++.dg/template/dr1710.C | 9 +++ > gcc/testsuite/g++.dg/template/dr1794.C | 14 ++++ > gcc/testsuite/g++.dg/template/dr314.C | 15 ++++ > gcc/testsuite/g++.dg/template/error4.C | 3 +- > gcc/testsuite/g++.dg/template/meminit2.C | 4 +- > gcc/testsuite/g++.old-deja/g++.pt/crash38.C | 6 +- > 21 files changed, 221 insertions(+), 31 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl2.C > create mode 100644 gcc/testsuite/g++.dg/cpp1y/alias-decl3.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name10.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name11.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name12.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name13.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C > create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710-2.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1710.C > create mode 100644 gcc/testsuite/g++.dg/template/dr1794.C > create mode 100644 gcc/testsuite/g++.dg/template/dr314.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index 05363653691..753b3148ab3 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -6266,6 +6266,32 @@ cp_parser_unqualified_id (cp_parser* parser, > } > } > > +/* Check [temp.names]/5: A name prefixed by the keyword template shall > + be a template-id or the name shall refer to a class template or an > + alias template. */ > + > +static void > +check_template_keyword_in_nested_name_spec (tree name) > +{ > + if (CLASS_TYPE_P (name) > + && ((CLASSTYPE_USE_TEMPLATE (name) > + && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (name))) > + || CLASSTYPE_IS_TEMPLATE (name))) > + return; > + > + if (TREE_CODE (name) == TYPENAME_TYPE > + && TREE_CODE (TYPENAME_TYPE_FULLNAME (name)) == TEMPLATE_ID_EXPR) > + return; > + /* Alias templates are also OK. */ > + else if (alias_template_specialization_p (name, nt_opaque)) > + return; > + > + permerror (input_location, TYPE_P (name) > + ? G_("%qT is not a template") > + : G_("%qD is not a template"), > + name); > +} > + > /* Parse an (optional) nested-name-specifier. > > nested-name-specifier: [C++98] > @@ -6389,7 +6415,17 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > /* Look for the optional `template' keyword, if this isn't the > first time through the loop. */ > if (success) > - template_keyword_p = cp_parser_optional_template_keyword (parser); > + { > + template_keyword_p = cp_parser_optional_template_keyword (parser); > + /* DR1710: "In a qualified-id used as the name in > + a typename-specifier, elaborated-type-specifier, using-declaration, > + or class-or-decltype, an optional keyword template appearing at > + the top level is ignored." */ > + if (!template_keyword_p > + && typename_keyword_p > + && cp_parser_nth_token_starts_template_argument_list_p (parser, 2)) > + template_keyword_p = true; > + } > > /* Save the old scope since the name lookup we are about to do > might destroy it. */ > @@ -6580,18 +6616,8 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser, > if (TREE_CODE (new_scope) == TYPE_DECL) > new_scope = TREE_TYPE (new_scope); > /* Uses of "template" must be followed by actual templates. */ > - if (template_keyword_p > - && !(CLASS_TYPE_P (new_scope) > - && ((CLASSTYPE_USE_TEMPLATE (new_scope) > - && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (new_scope))) > - || CLASSTYPE_IS_TEMPLATE (new_scope))) > - && !(TREE_CODE (new_scope) == TYPENAME_TYPE > - && (TREE_CODE (TYPENAME_TYPE_FULLNAME (new_scope)) > - == TEMPLATE_ID_EXPR))) > - permerror (input_location, TYPE_P (new_scope) > - ? G_("%qT is not a template") > - : G_("%qD is not a template"), > - new_scope); > + if (template_keyword_p) > + check_template_keyword_in_nested_name_spec (new_scope); > /* If it is a class scope, try to complete it; we are about to > be looking up names inside the class. */ > if (TYPE_P (new_scope) > @@ -18120,6 +18146,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, > } > } > } > + /* DR 1812: A < following a qualified-id in a typename-specifier > + could safely be assumed to begin a template argument list, so > + the template keyword should be optional. */ > + else if (parser->scope > + && qualified_p > + && typename_p > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) > + { > + cp_parser_parse_tentatively (parser); > + > + type = cp_parser_template_id (parser, > + /*template_keyword_p=*/true, > + /*check_dependency_p=*/true, > + none_type, > + /*is_declaration=*/false); > + /* This is handled below, so back off. */ > + if (type && concept_check_p (type)) > + cp_parser_simulate_error (parser); > + > + if (!cp_parser_parse_definitely (parser)) > + type = NULL_TREE; > + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) > + type = make_typename_type (parser->scope, type, typename_type, > + /*complain=*/tf_error); > + else if (TREE_CODE (type) != TYPE_DECL) > + type = NULL_TREE; > + } > > /* Otherwise, look for a type-name. */ > if (!type) > diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > new file mode 100644 > index 00000000000..e5397e71bd6 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl1.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile { target c++14 } } > + > +template <int> struct S { > + template <int> struct A; > + template <int N> using U = typename A<N>::foo; > +}; > +template <typename T> typename S<1>::U<T::foo>::type a; > +template <typename T> typename S<1>::template U<T::foo>::type a2; > diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C > new file mode 100644 > index 00000000000..f42b425a30b > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl2.C > @@ -0,0 +1,8 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile { target c++14 } } > + > +template <typename T> struct S { > + template <typename TT> > + using U = TT; > +}; > +template <typename T> typename S<int>::template U<T>::type foo; > diff --git a/gcc/testsuite/g++.dg/cpp1y/alias-decl3.C b/gcc/testsuite/g++.dg/cpp1y/alias-decl3.C > new file mode 100644 > index 00000000000..b950b20b5d8 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp1y/alias-decl3.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile { target c++14 } } > + > +template <typename T> struct S { > + template<typename TT> struct A { }; > + typedef A<int> type; > +}; > +template <typename T> typename S<int>::template A<int> foo; > +template <typename T> typename S<int>::template type foo2; // { dg-error "expected template-id" } > diff --git a/gcc/testsuite/g++.dg/parse/missing-template1.C b/gcc/testsuite/g++.dg/parse/missing-template1.C > index fcc3aa0c3ff..19c1433d09f 100644 > --- a/gcc/testsuite/g++.dg/parse/missing-template1.C > +++ b/gcc/testsuite/g++.dg/parse/missing-template1.C > @@ -12,9 +12,7 @@ template <typename T> struct A > > template <typename T> void foo() > { > - typedef typename A<T>::B<T>::X Y; // { dg-error "non-template" "non" } > - // { dg-error "not declare" "decl" { target *-*-* } .-1 } > - // { dg-message "note" "note" { target *-*-* } .-2 } > + typedef typename A<T>::B<T>::X Y; > } > > void bar() > diff --git a/gcc/testsuite/g++.dg/parse/template3.C b/gcc/testsuite/g++.dg/parse/template3.C > index c284a5ee040..8da8a48a3c3 100644 > --- a/gcc/testsuite/g++.dg/parse/template3.C > +++ b/gcc/testsuite/g++.dg/parse/template3.C > @@ -13,7 +13,4 @@ struct X : Outer<b>::template Inner<T> > {}; > > template <bool b, typename T> > -struct Y : Outer<b>::Inner<T> {}; // { dg-error "used as template" "temp" } > -// { dg-error "expected" "exp" { target *-*-* } .-1 } > -// { dg-message "note" "note" { target *-*-* } .-2 } > - > +struct Y : Outer<b>::Inner<T> {}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name10.C b/gcc/testsuite/g++.dg/template/dependent-name10.C > new file mode 100644 > index 00000000000..18e024f7e6d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name10.C > @@ -0,0 +1,18 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> struct B { > + typedef int TT; > + typedef int TT2; > + typedef int TT3; > + typedef int TT4; > + }; > +}; > + > +struct X : A<int>::B<int> { > + using A<int>::template B<int>::TT; > + using typename A<int>::template B<int>::TT2; > + using A<int>::B<int>::TT3; > + using typename A<int>::B<int>::TT4; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name11.C b/gcc/testsuite/g++.dg/template/dependent-name11.C > new file mode 100644 > index 00000000000..687a9bd5df5 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name11.C > @@ -0,0 +1,15 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile { target c++11 } } > + > +template<typename T> struct A { > + template<typename U> > + struct W { }; > +}; > + > +void > +g () > +{ > + // class-key nested-name-specifier template[opt] simple-template-id > + struct A<int>::W<int> w; > + struct A<int>::template W<int> w2; > +} > diff --git a/gcc/testsuite/g++.dg/template/dependent-name12.C b/gcc/testsuite/g++.dg/template/dependent-name12.C > new file mode 100644 > index 00000000000..7ee94e7457d > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name12.C > @@ -0,0 +1,7 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > + > +template <bool> struct A; > +template <typename, typename> struct B; > +template <typename T, typename U, typename V> struct B<T U::*, V> { > + typename A<V::x>::type::type t; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name13.C b/gcc/testsuite/g++.dg/template/dependent-name13.C > new file mode 100644 > index 00000000000..1e971168657 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name13.C > @@ -0,0 +1,8 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > + > +template<typename T> struct S { > + void fn(typename T::template B<int>::template C<int>); > + void fn2(typename T::B<int>::template C<int>); > + void fn3(typename T::template B<int>::C<int>); > + void fn4(typename T::B<int>::C<int>); > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C > index fc78983324b..15c1acb0347 100644 > --- a/gcc/testsuite/g++.dg/template/dependent-name5.C > +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C > @@ -22,9 +22,7 @@ struct A > > typedef N<int> type6; > typedef A::N<int> type7; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T>::N<int> type8; > -// { dg-error "" "" { target c++2a } .-1 } > typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } > typedef typename A<T*>::template N<int> type10; > > diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C > new file mode 100644 > index 00000000000..3dfa42d2df0 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(A<T>::B<U>&); > + void fn(A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C > new file mode 100644 > index 00000000000..ad9e44f9b85 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::B<U>&); > + void fn(typename A<T>::B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C > new file mode 100644 > index 00000000000..6dfdbc176c1 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C > @@ -0,0 +1,9 @@ > +// PR c++/94057 - template keyword in a typename-specifier. > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + B(typename A<T>::template B<U>&); > + void fn(typename A<T>::template B<U>); > + }; > +}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710-2.C b/gcc/testsuite/g++.dg/template/dr1710-2.C > new file mode 100644 > index 00000000000..99d49b746b2 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710-2.C > @@ -0,0 +1,10 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct A { > + template<typename U> struct B { > + }; > +}; > + > +template<typename T> struct D : A<int>::B<int> {}; > +template<typename T> struct D2 : A<int>::template B<int> {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1710.C b/gcc/testsuite/g++.dg/template/dr1710.C > new file mode 100644 > index 00000000000..c945977971f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1710.C > @@ -0,0 +1,9 @@ > +// DR 1710 - Missing template keyword in class-or-decltype > +// { dg-do compile } > + > +template<typename T> struct D : T::template B<int>::template C<int> {}; > +template<typename T> struct D2 : T::B<int>::template C<int> {}; > +template<typename T> struct D3 : T::template B<int>::C<int> {}; > +template<typename T> struct D4 : T::B<int>::C<int> {}; > +template<typename T> struct D5 : T::template B<int>::type::type {}; > +template<typename T> struct D6 : T::B<int>::type::type {}; > diff --git a/gcc/testsuite/g++.dg/template/dr1794.C b/gcc/testsuite/g++.dg/template/dr1794.C > new file mode 100644 > index 00000000000..f629d7d0b98 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr1794.C > @@ -0,0 +1,14 @@ > +// DR 1794 - template keyword and alias templates. > +// { dg-do compile { target c++11 } } > + > +template<template<typename> class Template> > +struct Internal { > + template<typename Arg> > + using Bind = Template<Arg>; > +}; > + > +template<template<typename> class Template, typename Arg> > +using Instantiate = Template<Arg>; > + > +template<template<typename> class Template, typename Argument> > +using Bind = Instantiate<Internal<Template>::template Bind, Argument>; > diff --git a/gcc/testsuite/g++.dg/template/dr314.C b/gcc/testsuite/g++.dg/template/dr314.C > new file mode 100644 > index 00000000000..7c0d8ac592f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/dr314.C > @@ -0,0 +1,15 @@ > +// DR 314 - template in base class specifier. > + > +template <typename T> > +struct A { > + template <typename U> > + struct B {}; > +}; > + > +template <typename T> > +struct C : public A<T>::template B<T> { > +}; > + > +template <typename T> > +struct C2 : public A<int>::B<T> { > +}; > diff --git a/gcc/testsuite/g++.dg/template/error4.C b/gcc/testsuite/g++.dg/template/error4.C > index 9d76561aa02..a5030f06c98 100644 > --- a/gcc/testsuite/g++.dg/template/error4.C > +++ b/gcc/testsuite/g++.dg/template/error4.C > @@ -5,5 +5,4 @@ template<class T> struct C1 > }; > > template<class T, class U> > -void foo(typename C1<T>::C2<U>::Type *) { } // { dg-error "template" "error " } > -// { dg-message "note" "note" { target *-*-* } .-1 } > +void foo(typename C1<T>::C2<U>::Type *) { } > diff --git a/gcc/testsuite/g++.dg/template/meminit2.C b/gcc/testsuite/g++.dg/template/meminit2.C > index db6e0427fc7..6a56a806746 100644 > --- a/gcc/testsuite/g++.dg/template/meminit2.C > +++ b/gcc/testsuite/g++.dg/template/meminit2.C > @@ -14,8 +14,6 @@ struct A : typename O<T>::template I<int> { // { dg-error "keyword 'typename' > > template <typename T> > struct B : O<T>::template I<int> { > - B() : O<T>::I<int>() // { dg-error "used as template|it is a template" } > + B() : O<T>::I<int>() > {} > }; > - > -// { dg-bogus "end of input" "bogus token skipping in the parser" { xfail *-*-* } 17 } > diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > index 5d386132436..60cd5e3f44e 100644 > --- a/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > +++ b/gcc/testsuite/g++.old-deja/g++.pt/crash38.C > @@ -3,10 +3,8 @@ > > template <class T> > struct S { > - typedef typename T::Y<T>::Z X; // { dg-error "non-template" "non-template" } No Y in A > -// { dg-message "note" "note" { target *-*-* } .-1 } > -// { dg-error "does not declare" "not declare" { target *-*-* } .-2 } > - X x; // { dg-error "does not name a type" } No Y in A > + typedef typename T::Y<T>::Z X; // { dg-error "not a class template" } No Y in A > + X x; > }; > > struct A { > > base-commit: 16948c54b7576fb4b27c59915eac71a0c6bf94f6 >
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index cbd5510a8fb..f4175955992 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -18113,6 +18113,33 @@ cp_parser_simple_type_specifier (cp_parser* parser, } } } + /* DR 1812: A < following a qualified-id in a typename-specifier + could safely be assumed to begin a template argument list, so + the template keyword should be optional. */ + else if (parser->scope + && qualified_p + && typename_p + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID)) + { + cp_parser_parse_tentatively (parser); + + type = cp_parser_template_id (parser, + /*template_keyword_p=*/true, + /*check_dependency_p=*/true, + none_type, + /*is_declaration=*/false); + /* This is handled below, so back off. */ + if (type && concept_check_p (type)) + cp_parser_simulate_error (parser); + + if (!cp_parser_parse_definitely (parser)) + type = NULL_TREE; + else if (TREE_CODE (type) == TEMPLATE_ID_EXPR) + type = make_typename_type (parser->scope, type, typename_type, + /*complain=*/tf_error); + else if (TREE_CODE (type) != TYPE_DECL) + type = NULL_TREE; + } /* Otherwise, look for a type-name. */ if (!type) @@ -23636,8 +23663,9 @@ cp_parser_class_name (cp_parser *parser, && decl != error_mark_node && !is_overloaded_fn (decl)) { - decl = make_typename_type (scope, decl, typename_type, - /*complain=*/tf_error); + tsubst_flags_t complain = (cp_parser_parsing_tentatively (parser) + ? tf_none : tf_error); + decl = make_typename_type (scope, decl, typename_type, complain); if (decl != error_mark_node) decl = TYPE_NAME (decl); } diff --git a/gcc/testsuite/g++.dg/template/dependent-name5.C b/gcc/testsuite/g++.dg/template/dependent-name5.C index fc78983324b..15c1acb0347 100644 --- a/gcc/testsuite/g++.dg/template/dependent-name5.C +++ b/gcc/testsuite/g++.dg/template/dependent-name5.C @@ -22,9 +22,7 @@ struct A typedef N<int> type6; typedef A::N<int> type7; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T>::N<int> type8; -// { dg-error "" "" { target c++2a } .-1 } typedef A<T*>::template N<int> type9; // { dg-error "" "" { target c++17_down } } typedef typename A<T*>::template N<int> type10; diff --git a/gcc/testsuite/g++.dg/template/dependent-name7.C b/gcc/testsuite/g++.dg/template/dependent-name7.C new file mode 100644 index 00000000000..3dfa42d2df0 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name7.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(A<T>::B<U>&); + void fn(A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name8.C b/gcc/testsuite/g++.dg/template/dependent-name8.C new file mode 100644 index 00000000000..ad9e44f9b85 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name8.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::B<U>&); + void fn(typename A<T>::B<U>); + }; +}; diff --git a/gcc/testsuite/g++.dg/template/dependent-name9.C b/gcc/testsuite/g++.dg/template/dependent-name9.C new file mode 100644 index 00000000000..6dfdbc176c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/dependent-name9.C @@ -0,0 +1,9 @@ +// PR c++/94057 - template keyword in a typename-specifier. +// { dg-do compile } + +template<typename T> struct A { + template<typename U> struct B { + B(typename A<T>::template B<U>&); + void fn(typename A<T>::template B<U>); + }; +};
Consider template <typename T> class A { template <typename U> class B { void fn(typename A<T>::B<U>); }; }; which is rejected with error: 'typename A<T>::B' names 'template<class T> template<class U> class A<T>::B', which is not a type whereas clang/icc/msvc accept it. "typename A<T>::B<U>" is a typename-specifier. Sadly, our comments don't mention it anywhere, because the typename-specifier wasn't in C++11; it was only added to the language in N1376. Instead, we handle it as an elaborated-type-specifier (not a problem thus far). So we get to cp_parser_nested_name_specifier_opt which has a loop that breaks if we don't see a < or ::, but that means we can -- tentatively -- parse even B<U> which is not a nested-name-specifier (it doesn't end with a ::). Even though we're parsing B<U> tentatively, we issue an error in cp_parser_class_name -> make_typename_type, but here we should not. In fact, we probably shouldn't have parsed "B<U>" at all. Fixed by the cp_parser_class_name hunk. I think this should compile because [temp.names]/4 says: "In a qualified-id used as the name in a typename-specifier, elaborated-type-specifier, using-declaration, or class-or-decltype, an optional keyword template appearing at the top level is ignored.", added in DR 1710. Also see DR 1812. This issue on its own is not a significant problem or a regression. However, in C++20, the typename here becomes optional, and so this test is rejected in C++20, but accepted in C++17: template <typename T> class A { template <typename U> class B { void fn(A<T>::B<U>); }; }; Here we morph A<T>::B<U> into a typename-specifier, but that happens in cp_parser_simple_type_specifier and we never handle it as above. To fake the template keyword I'm afraid we need to use cp_parser_template_id with template_keyword_p=true as in the patch below. The tricky thing is to avoid breaking concepts. Does this approach make sense? Should these tests be accepted because of DR 1710 or am I off base here? Apologies for the verbosity, but I felt it necessary. Bootstrapped/regtested on x86_64-linux, built Boost/cmcstl2, ok for trunk? PR c++/94057 - template keyword in a typename-specifier. * parser.c (cp_parser_simple_type_specifier): Assume that a < following a qualified-id in a typename-specifier begins a template argument list. (cp_parser_class_name): Complain only if not parsing tentatively. * g++.dg/template/dependent-name5.C: Update dg-error. * g++.dg/template/dependent-name7.C: New test. * g++.dg/template/dependent-name8.C: New test. * g++.dg/template/dependent-name9.C: New test. --- gcc/cp/parser.c | 32 +++++++++++++++++-- .../g++.dg/template/dependent-name5.C | 2 -- .../g++.dg/template/dependent-name7.C | 9 ++++++ .../g++.dg/template/dependent-name8.C | 9 ++++++ .../g++.dg/template/dependent-name9.C | 9 ++++++ 5 files changed, 57 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/template/dependent-name7.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name8.C create mode 100644 gcc/testsuite/g++.dg/template/dependent-name9.C base-commit: f22712bd8a2ed57d3cc7e6fa92730bd5852e27b3